Wecome To RVs and OHVs

This blog is all about RVs (recreational vehicles) and OHVs (Off Highway Vehicles), camping, sailing, and survival
and how they work together to provide wholesome family fun and great learning opportunities.
Many posts are intended to familiarize novice campers and RVers with RV systems and basic camping and survival
skills. But even experienced RVers and campers will enjoy the anecdotes and may even benefit from a new
perspective. Comments, questions, and suggestions are encouraged. The organization is pretty much by date of publication because of how blogspot works. Please use the SEARCH option below to find what you are looking for.

Thursday, September 30, 2021

Chain Saws For Campers

Chain saws are essential for off-grid living and very useful for homeowners with lots of trees on their property.  Because of their size and their cost they aren't always adopted by RVers and campers.  Campers traditionally rely simple bow saws or foldable saws because they are small and inexpensive.  So-called cable saws are very small and easy to transport and pretty easy to use, but they can take a lot of time and effort to cut through larger pieces of wood.   Manual saws (like bow saws or buck saws) have a been a staple for campers for decades.  They are quiet and reliable but take up a lot of room and take a lot of effort to use.  But, with new, quiet, lightweight cordless chain saws that might be changing. Small, handheld cordless chain saws are available with blades up to 6" that might be handy for campers and RVers.

Chain saws are handy tools for cutting firewood for camping.  These days you can choose from gasoline powered, electric powered, and cordless models.   I even have an older 12-volt model that runs off a car battery.   A good chain saw with a sharp chain can make short work of cutting logs into firewood.  If you camp where you legally gather firewood a chain saw might be a useful addition to your camp kit or RV.

The most popular and most powerful chain saws are gasoline powered.  They normally have a 2-stroke engine that requires oil to be mixed with the gasoline.  Running unmixed gas in a 2-stroke engine will result in catastrophic engine failure as 2-strokes rely on the oil in the gasoline to lubricate the engine.   Be sure to use the prescribed ratio.  A mixture that is too rich (too much oil) will foul the spark plug and one that is too lean (too little oil) will cause excessive wear or even cause the engine to seize.  Every engine has a prescribed fuel:oil ratio.  The typical ratio for many chain saws is 50:1 (50 parts gasoline for 1 part oil).  You can calculate how much oil you  need to add to your gas can or use a device like a Ratio-rite that is calibrated to measure the amount of oil for several common ratios and common gas can sizes.  There are often special, richer "break in"ratios needed for new engines.  Running the standard ratio during break in may result in engine damage.  Running the break in ratio beyond the break in period can result in fouling spark plugs and excess smoke so be sure to use the break in ratio for the break in period and only the break in period.  Gasoline powered chain saws come in many sizes.  The larger sizes are quiet heavy.  All gasoline chain saws are noisy.  You will want to wear ear protection when using them, especially for extended periods of time.

Electrical chain saws are handy for small tasks like cutting firewood but you need a long extension cord of adequate gauge and a source of 120 VAC power.  Using too small a gauge extension cord can cause a number of problems, including reduced performance, shortening motor life, blown fuses or circuit breakers, and even overheating and melting the cord and possible fires.  Most RV generators and many portable generators provide more than adequate power to run an electric chain saw.  You may even be able run one on a portable inverter attached to a 12 volt battery.

Cordless chain saws are a fairly recent addition to the market.  Cordless chain saws are particularly convenient for RVers and campers.  They are generally lighter than gasoline saws, much quieter, and do not require cumbersome electrical cords or an immediate 120 V power source during operation.  You do need a 120 V power source to recharge the batteries but not during normal operation.  If you opt for a cordless chain saw you may want to purchase extra batteries so you always have enough charged batteries available to last until you can recharge them.  A solar powered battery charger may allow you to conveniently, quietly, and inexpensively recharge your batteries whenever you have sunlight.  Or just make sure to put the batteries on the charger and run your RV generator for a while after each use.  

The recent addition of small, one-handed, cordless chain saws gives RVers and campers even greater convenience and flexibility.  They usually aren't big or tough enough to cut logs, but can be useful for trimming firewood to fit your needs and are getting inexpensive enough and small enough to make it worthwhile for camping.  The one I bought included three 4"chains, 2 extra bars, 2 batteries and a charger, and even gloves and safety glasses, all in a convenient plastic case that will easily fit in just about any storage cabinet on an RV or camper.  It is not much bigger than a kids metal lunch box.  It was on sale at Christmas for under $50 on Amazon.com.  Regular prices start around $55.  Be sure to check the sizes.  For example some have 4" blades, some have 6" blades.  Finally got a chance to try mine out and was very pleased.  The 4" blade isn't going to handle big logs but it sure made trimming branches up to 2-4" or so fast and easy!  It doesn't have a chain oiler so I would be concerned about using it continuously for long periods without oiling it or letting the chain cool down.  It has quickly become my favorite yard trimming tool.

I have an older 12-volt chain saw that runs off a car battery that I carry in my RV but they are not easy to find these days.  Quite frankly, the one I have, which I bought at a garage sale many years ago, is the only one I've ever actually seen!  I did locate new ones online called a Minibrute that is similar to the one I have.  The only downside is you need to be fairly close to your vehicle (about 10-12') or drag a heavy 12-volt battery pack or portable generator with you to your work site.

Chain saws, like any power tool, require proper training for safe usage.   In fact, chain saws really need a lot more training than other common homeowner power tools.  To  use a chain saw on U.S. Forest Service lands you even have to pass a training and certification requirement.  Most, but not all, chain saw injuries are the result of user error and are preventable.    Here is a basic introductory training video.  In this video they will stress the importance of getting hands-on instruction from a qualified  instructor.  If you watch the video all the way through it should go into a second video that offers instruction on how to cut trees if you are interested in doing that.  You may even be required to be certified to operate a chain saw in many state and Federal forests if you plan to cut your own firewood for camping.

Modern chain saws include a chain brake.  It looks like second handle in front of the handle on the motor and is designed to stop the chain if your hand hits it (like it does if the saw hits something and bucks).  The brake is pushed toward the back of the saw to use the saw and brakes the chain when pushed forward.  If the saw bucks it kicks back toward you and your hand or wrist usually pushes the brake forward and activates it to stop the chain.  The brake often needs to be in the off position to start the saw.  Some older saws do not have chain brakes.  If for some reason you happen to have one of these older saws, be especially careful when operating it as the chain brake on modern units is a significant safety feature.  Never remove or disable any safety device!

Personal Protection Equipment (PPE) is essential for safe operation.  Minimum equipment would include sturdy work gloves and eye protection (safety goggles or face shield).  I like goggles with a fine mesh screen for cold weather use because they won't fog up.   Hard hats are suggested to protect your head from flying wood tossed by the saw if it jams or if you are trimming trees to prevent injury if a falling limb or piece of wood kicked up by the saw lands your head.  Hearing protection is also highly recommended, especially for gasoline powered models and particularly if you are going to be doing a lot of cutting.  Special chainsaw chaps are more than a good idea, they should be considered essential!  They are designed to stop the chain quickly to prevent serious injury to your legs.  Note that chaps will usually stop gasoline engines, but electric motors will continue to run as long as they have power and the switch is on, even if the chain is inhibited by the chaps.  Regular pants, even  Levis and sturdy off-road riding pants will not prevent chain saw injuries.  Not even our ultra-heavy firefighter turn-out pants will protect against a chainsaw and we are always required to wear chaps when using a chain saw in the fire service.

Ensuring your work area is safe and clear of people or hazards is critical.    The area should be free of branches or debris that would interfere with safe operation.  Be sure to check overhead as well as all around your work area.   One good way to ensure a clear area is to take a stick about the length of our chainsaw and swing it all around and over head.  If it doesn't hit anything, you should be clear.  If it does hit something you either need to clear the obstacle or find another place to do your cutting.  Even if there is nothing directly in the way of what you are cutting you need to make sure the area around you is clear.  If the saw jams and bucks it is likely to swing anywhere within reach, injuring or damagig anyone or anything it comes in contact with and possible bouncing back to injure you!  When cutting firewood you will want to have some kind of base beneath the log your are cutting.  You NEVER want to let the chain cut into the ground.  It will dull the saw almost instantly.  Chains are designed to cut wood, not dirt!

A sharp chain is essential to both ease of operation and safety.   A dull chain will make you work harder and is more likely to bind or kickback which often results in injuries.  If you see smoke coming from where you are cutting, you need to sharpen your chain!  If there are burned or scorched marks in the cut, you need to sharpen your chain!  Eventually a dull chain could even start a fire!  A dull chain also places more load on the motor accelerating wear and shortening usable life.

Gasoline powered chain saws are very noisy.   You should always wear ear protection when using them, especially if you are going to be using them for any length of time.  You also need to be aware of the impact the noise may have on fellow campers and restrict your usage to times of the day and locations  that will minimize any impact on other people.

Safe starting of gasoline chain saws.   First, make sure the area around you is safe, free from obstacles that might interfere and people who might be injured.  People should always be at least 10-15 feet away when you start the saw in case the chain catches on something and kicks back.  You may see loggers starting a chain saw using a drop method where they hold the handle of the starting rope and drop the saw to start it.  This it NOT an approved method.  Two safe ways to start a saw are to hold the back end of the saw securely between your knees while pulling the rope or to set the saw on the ground and put the toe of one boot into the handle beneath the trigger while yanking the rope.  No matter which method you use ALWAYS set the chain brake off before attempting to start the saw.  Most saws have a 2-step choke.  Typically you will push the choke all the way down and pull the rope until the engine pops, then move the choke to the center position and start the saw. Once it is running, open the choke fully.  Some saws (especially larger ones)  have a compression release button.  Pressing this button before attempting to start the saw is essential since high-compression engines will be too hard to turn over to start under full compression.

All chain saws need bar oil.  This is a special grade of oil designed to lubricate the chain.  Old time saws sometimes required you to squeeze the trigger frequently to squirt oil on the chains but modern saws do it automatically.  Fill the oil on the saw every time you fill the gas.  A "tank" of bar oil usually lasts through at least one tank of gas..  Most saws have a visual window where you can see how much oil is remaining so you can top off if necessary before you ruin a chain by running it dry!  Most oil tanks are designed to hold enough oil to last more than the fuel in the fuel tank so refilling the oil each time you fill the fuel should prevent you from running out of oil.  If you are using an electric, cordless, or 12 volt saw, be sure to keep an eye on the oil level or keep track of how much time you've been running the saw and how often you have to refill the oil so you can keep enough oil in the tank at all times.  Running a chain saw without oil is a sure recipe for disaster!  Lack of oil will cause the chain to overheat and to wear more quickly or possibly even bind up.  If you happen to run out of bar oil, in a pinch you might use 10-30 motor oil.  It won't perform as well as specially formulated bar oil and will probably splatter but it will provide some lubrication and reduce possible damage.  For the small, hand-held chain saws that don't have an oiler, dribble a little chain oil on the chain from time to time to prevent excess wear.

You can purchase chain saws at just about any home center, on Amazon.com, and places like Harbor FreightLike most power tools for home use they do not require any special licenses to buy them.  However, you should make sure you get proper instruction from an experienced chain saw user or qualified instructor before you try to use your new saw.  They are far more dangerous and require more training and skill for safe operation than typical homeowner power equipment like a cordless drill or circular saw.

Chain through!

Wednesday, September 29, 2021

Harbor Freight forTools and Supplies for RVers, OHVers, Campers and Boaters

I have mentioned Harbor Freight in a number of posts.  That is not because I receive any sponsorship or compensation from Harbor Freight, it is just because I have some experience with the products involved and have found them to be useful and cost effective and thought my readers might too.  They have lots of hand tools, power tools, garden tools, and other items that are useful to campers -- like tie downs, towing products, tarps, hardware, and even wheels and tires that fit some small tent trailers.  I became really familiar with their products when my wife worked as a rebuyer for their purchasing department.

You can find lots of Youtube videos about Harbor Freight tools.  They will include both positive and negative opinions.  Be sure to consider the background, qualifications, and bias of the reviewer together with both their intended use of the tools and your intended use.  You may need professional quality tools if you use them regularly on your job but less expensive options may be adequate for home or DIY use.

I have found Harbor Freight to be an excellent source for many tools for my RVs, OHVs, boats, and camping as well as for my mechanics and home maintenance tools.   You will sometimes see negative comments about the quality of tools from Harbor Freight.  While it is almost certain that high end name brands like SnapOn, Husky, and Craftsman will most likely last longer in professional use, I have pretty much found Harbor Freight tools to be more than adequate for my do it yourself projects.  The lower cost also allows me to purchase specialty tools that make jobs easier and sometimes allow me to do tasks that I could not otherwise do at all.  It also lets me afford duplicates to create convenient specialized tool kits for my motorcycle trailer, camp kit, RV, and boat.  Harbor Freight also offers a lifetime guarantee on just about all their hand tools.  In more than twenty years of buying and using their tools I have only had to utilize the guarantee a couple of times and both times they were very quick and friendly about replacing the damaged items, no questions asked.

Harbor Freight offers about the biggest selection of tarps I have seen anywhere.   They include light weight blue "poly" tarps, green farm tarps, more heavy duty silver tarps, and even real canvas tarps.  The selection and reasonable pricing always makes them my first stop when I need a tarp.  The normal prices are usually pretty good but keep an eye out for coupons and sales for even better savings.  Of course you an also find really light clear plastic painter's tarps too.

Another pretty complete category of useful items for RVers is the towing section.  You will find hitches, couplers, ball mounts, towing balls, lights, hitch pins, tie downs, safety chains, towing straps, anti-sway bars, tongue jacks, just about everything you need for towing trailers and even hitch-mount racks for carrying additional cargo and mounting winches.

Harbor Freight offers a variety of jacks and jack stands that can be useful, ranging from small bottle jacks to 10-ton floor jacks and tall farm jacks like the ones often used off-road by 4x4 users.

Harbor Freight has a large selection of hand tools -- wrenches, pliers, screw drivers, sockets, ratchets, hammers, clamps, and pry bars.  They also provide a lifetime warranty on almost all of their hand tools.  I have had to use the warranty a couple of times.  One time I twisted a socket completely off of a cross-bar lug wrench trying to remove a stuck lug not on a 3/4 ton off-road truck.  Another time I twisted a T-handle allen wrench until the flat sides were twisted from tip to  handle.  I was impressed with the strength of the plastic handle!  In both cases I was clearly exceeding the normal application but received replacements on the spot without any hassle.

The reviews of Harbor Freight power tools are mixed.  If you look for Harbor Freight on Youtube you will get a variety of videos listing the "10 Best" or "10 worst" Harbor Freight items.  Sometimes they may tell you what to buy or not to buy at Harbor Freight.  Remember, all of these videos are personal opinions of the people who made the videos and they may or may not have their own bias and they may or may not have any real qualifications for evaluating the products.  My own experience has been mostly positive.  I have found things like cordless drills and even cordless impact wrenches to be well worth the modest price.  Did they hold up as long as brand names like Dewalt?  No, not usually.  But the prices were significantly less and usually the performance was similar or at least adequate while they lasted for my DIY projects.  In general I have found most DIY reviews were pretty positive while many of the negative reviews were from professionals who normally use expensive, high-end tools and use them a lot.  An inexpensive cordless drill was a welcome addition to the tools in my enclosed motorcycle trailer.

Harbor Freight offers a wide assortment of portable generators, ranging from small "tailgater" units to large ones that provide enough power to run your whole house in an emergency.   I have seen Youtube videos that both praise and criticize Harbor Freight generators.  Generally the ones from Harbor Freight will be considerably less expensive than well know name brands and may still be a good value even if they don't meet the same performance or longevity of the higher priced brands.  I have a 4500 watt unit I use frequently due to power outages in my rural area and in the two or three years I've had it, it has performed flawlessly.  It cost way less than half a "brand name"generator of the same size.

Harbor Freight is offering a line of winches that is an extraordinary value.   I have personally used a couple of their 2500 lb ATV winches and been very satisfied with them.  I have been eyeing the 12,000 lb Badlands winch for my 4WD truck.  At a regular retail price of $599 it is about 1/3 the cost of a similarly rated name brand winch and I have seen several very favorable reviews on Youtube from highly qualified professional users.  I have even noticed that a couple of popular off-road recovery teams uses the 12,000 lb Badlands winch.  I recently saw the 12,000 lb Badlands winch on sale for just $319!  And they have a hitch-mount rack specifically designed for it for just $75.  A similarly sized Warn brand winch typically retails for around $1800!

Harbor Freight has recently introduced some higher priced hand and power tools.  These might be of particular interest to professionals or those whose budgets can accommodate the higher prices.   Supposedly they will be closer in fit, finish, and quality to the high-end name brand tools but still less expensive.  When purchasing hand tools, especially things like pliers and wrenches and sockets, I look at the fit and finish and prefer those with precise edges and a smooth, shiny finish.  I have seen wrenches that looked like they had been cast in sand molds and avoid them!  Most of the hand tools that have failed me in the past would not have passed my current fit and finish selection criteria.  A lot of the wrenches and socket sets at Harbor Freight have a very nice fit and finish.

Harbor Freight often offers a variety of hardware you won't find any place else.  I find their "storehouse" offerings particularly appealing.  These are collections of small parts (nuts, bolts, fasteners, o-rings, nylon clamps, hitch pins, cotter keys, etc).  They usually come with their own plastic storage bins to organize them for ease of use.  A quick glance at my supply cabinet shows o-rings, hitch pins, cotter keys, metric nuts and bolts, SAE nuts and bolts, hose rings, hose clamps and cable clamps.  Having an assortment of commonly used hardware on hand has saved many projects and many trips to town!  They also usually have a good assortment of cable ties, ranging from tiny little ones handy for controlling phone charger cables to huge ones big enough to secure tents and sleeping bags.  On a related note, I figured out a way to keep the little plastic tubs in my dirt bike trailer nut and bolt storehouse from sliding out when traveling:  I cut some pieces of thin welding rod to match the height and width of the cabinet, then heated the ends and suck them into the plastic frames so they crossed in front of the drawers. It was a quick, cheap, and easy way to keep things from getting tossed all over the place towing the trailer to off-road locations.

Garden tools.  There are a surprising number of garden tools that might be useful for campers as well as for home use.  Axes, wedges, rakes, bow and pruning saws, and shovels are among the most appropriate camping choices as well as chain saws. Harbor Freight offers gasoline, electric, and cordless chain saws.  Bow saws and folding pruning saws are especially well suited for camping.   Folding saws are handy if you are hiking or backpacking.  Bow saws are a little stronger, cut faster, and are easier to use if you have a place to carry them,

Harbor Freight also has a wide assortment of gloves:  work gloves, garden gloves, welding gloves, mechanics gloves, latex gloves.  I rely almost exclusively on work and latex gloves from Harbor Freight for my home improvement, yard, RV, boat and car maintenance projects.  Their regular prices are usually very reasonable and they often have coupons that make them even more affordable.  I have noticed a dramatic increase recently in the cost of latex and nitrile gloves, thanks to COVID-19!

I have found  many uses for foam anti-fatigue mats which Harbor Freight has at a good price .  Be sure to watch for coupons for even greater savings, sometimes as low as $4.99 for 4-6 mats!  I have them in front of the workbench in my garage and in my motorcycle trailer.  I have also used them for a comfortable, anti-skid deck around and under my inflatable spa.  They can also be used to insulate the inside of boat cabins and are especially nice around the v-berth so you don't rub up against the cold fiberglass or metal hull in the middle of the night.  In addition to insulating the hull, the pads also reduce condensation inside the boat.

Harbor Freight stocks a good supply of safety items, such as goggles and face masks.   You will also find lot of other safety products, some you might not even have thought about before.  It can be educational just looking through the safety section.  I picked up some non-skid tape that has been useful on my RV, my motorcycle trailer, a utility trailer, and my sailboat as well as around the house.

Harbor Freight used to regularly offer coupons via print ads in many publications but has recently switched to online coupons.  Their coupons often provide substantial savings on their already low prices.  Use your favorite search engine to look for "Harbor Freight Coupons" to get the best prices on things you need.  Sometimes I peruse the coupons and take advantage of them to get items I might not even have an immediate need for if they are at a good price if I think I might have a use for them someday.  I like to be prepared.  They usually have a 20% off any item coupon that is especially useful when buying higher priced items at regular price.  Coupons are often a way to get customers into a store in hopes they will buy other things.  That being said, I have never had any negative experience buying coupon-only items at Harbor Freight.

They also offer an ''Insider's Club'' that gives additional discounts on selected items from time to time.  There is a modest annual fee to maintain your Club status but you usually recoup the cost quickly, especially if you purchase more expensive items where the Club savings on one purchase can often offset the annual fee.

Many Harbor Freight stores have side-walk sales from time to time.  These an be an especially good time to get excellent bargains.  Sometimes the inventory includes returned items offered at substantial savings.  When we lived in southern California we were even close enough to take advantage of the large side-walk sale at their warehouse in Camarillo, California.

In summary, I generally find Harbor Freight tools and hardware to be a good value.   As always, you should examine anything you are buying to make sure it meets your personal needs.  I would look to their higher-end offerings or maybe even defer to brand names for ongoing professional use but do-it-your-selfers may be able to expand your tool inventory at reasonable prices from their standard lines, allowing you to add many tools that would be way outside your budget if you bought professional brands and they will more than likely hold up well in occasional homeowner use.

Tool up!

Thursday, September 23, 2021

Keeping Your Boat Cabin a Comfortable Temperature

Let's face it, we all like to be comfortable!

 If you have a climate controlled luxury yacht you can probably skip this post.   However, the rest of us might find some useful tips here for keeping our boat cabins a comfortable temperature.  The cabin temperature on smaller boats can be notoriously difficult to control.

It is often more difficult to maintain climate control on a boat than it is an RV.  Almost all RVs have some kind of furnace or heater for cold days and many have a roof A/C to keep it cool on hot days.  But boats, especially small boats like daysailers, have neither and, of course, open boats have none.   RVs usually have insulation and many small boat cabins have none.  Since boating is mostly a fair weather activity the lack of a heater usually isn't a problem but often keeping cool is.  Of course, heaters and A/Cs are not relevant on open boats, but controlling the climate inside any boat with a cabin can be an adventure in itself.  Climate control in open boats is pretty much an individual thing -- dress for (or stay out of) the weather.  However, you can add a bimini cover provide some shade against the summer sun for many boats and it might help keep the rain off.  If you need to keep warm, wear warmer clothes -- or head back to a warm clubhouse, tavern, cabin, or campfire on the shore.

Like any other inhabited area we would like our boat cabins to be a comfortable temperature.  Human beings are usually most comfortable when the air temperature is about 70-72F.  When it gets hotter we want a cooler environment; when it is colder we seek warmer places.  When it is hot outside we want our boat cabins to be cool.  When the weather is wet and cold we want a warm, dry place inside out of the cold, wind, and wet stuff.   Small boat cabins usually do a pretty good job of getting us out of the elements.  However, many times boat cabins are not well insulated making them more susceptible to outside temperatures.  Having the hull sit in the water often means a large part of the boat functions as a heat sink to absorb heat from inside the boat and makes it hard to keep it warm inside.  Uninsulated hulls transfer heat to the water quite efficiently.  On hot days that can be a real boon, but on colder days it means it is going to take more heat to keep the cabin warm than it would to maintain the temperature in an RV or a room of similar size.  Rubbing up or leaning against a cold fiberglass or metal hull in bed can really ruin your rest period!  Since boating is usually a mostly fair weather sport the most common temperature problem on boats is the cabins are usually too warm , so cooling a boat cabin is often more of a priority than heating.  However, an uninsulated hull can still be very uncomfortable to the touch, even on warm days. Rolling over against one on cold nights can be really chilling!

Because weight is almost always a significant factor for boats, they often lack any kind of insulation.  Many times you can add some insulation if you have direct access to the inside of the hull as you do any many small boats. Foam anti-fatigue mats are an easy way to insulate boat walls.  They are fairly light weight, easy to cut to shape, are flexible to fit curved surfaces, and can be simply secured with basic adhesives.  Dark gray or black are standard colors but you can also buy brightly colored tiles that might be more attractive.  They can be glued directly to the fiberglass or metal hull liner in many boats.  Applying them below the water line will be especially helpful in preventing heat loss through the hull to the water.  Having them above the water line will help keep unwanted heat out and desirable heat in.  Installed on the walls of the V-berth they give you a padded, insulated surface next to your bed, making it far more comfortable than pressing up against a cold (or hot!) uninsulated hull wall!  Using them on the floor also has anti-slip benefits.  Adding insulation can also reduce condensation on the inside of the hull and the foam pad is softer than the hull if you bump into it.  Make sure whatever you add doesn't significantly increase the displacement.  A few pounds won't affect most boats large enough to include any kind of enclosed cabin, but consider that even light weight insulation may add up more quickly than you expect if you are applying it to large spaces.  If the weight of your boat and normal gear and supplies is already close to its maximum safe displacement, be careful adding extra weight!  The cabins on some boats have an upholstered ceiling that helps minimize heat transfer in and out.  I have seen folks remove it for cosmetic purposes usually when it gets old and stained, but doing so ultimately allows more heat into the cabin in hot weather and more heat loss when it's cold.  If your boat lacks any kind of ceiling covering you might add some to make controlling the inside temperature a little easier.

A wind scoop can often be used with a ceiling hatch on just about any boat to capture any available breeze and direct it down into the cabin for ventilation and cooling.  There are even models that are omni-directional so they will work no matter which direction the wind is coming from.   When your boat is in motion there is usually enough apparent wind coming from the bow for a front-facing scoop to work well, but when moored or anchored you may have to adjust the scoop as the wind changes direction.  Remember to leave another hatch or window open so the incoming air has somewhere to go!  Otherwise you simply pressurize the cabin and you won't get any air movement inside.  Wind scoops work pretty well when the boat is in motion but unless you monitor them and realign them with the wind as necessary while anchored they will only work when facing the wind -- unless you have the omni-directional style which is generally more expensive and sometimes a little bulkier.

Sometimes you can keep a cabin cooler by protecting it from the sun with some kind of canopy or awning.   A simple tarp suspended over the cabin to shade the cabin and provide a shaded air buffer to keep it out of direct sunlight will help keep things cooler inside.  Simply draping a tarp over the cabin might help a little but may also conduct heat if it touches the cabin surface so having it a few inches away from the surface is better.  Using a reflective silver or white tarp will keep things cooler than using a dark blue or green tarp.  You can usually set up a "boom tent" on sailboats fairly easily using the boom when the mainsail isn't raised.  A boom tent can cool the cockpit as well as the cabin but is really only practical at anchor.  A more permanent cover called a "bimini" can be adapted to provide shade on many boats.  They are more practical on power boats because they get in the way of  the very necessary task of watching the sails on a sailboat.  Some creative owners have made biminis with clear panels so they get rain protection but can still see the sails.

Portals (windows) on boats are usually much smaller than windows on RVs and campers but they can still let in a lot of unwanted sunlight and heat on hot days.  If you find you are getting unwanted heat through windows, cover them with reflective film or even total blackout film or hang curtains over them to block the sunlight.  You might be surprised how much cooler your cabin will be on hot sunny days when you limit sunlight intrusion!  Of course, smaller openings also don't work as well to help cool things when needed.

On larger boats, you may have the option of installing an air conditioner to cool things down on hot days.  Air conditioners are generally too heavy and too bulky to be used on smaller boats plus you need a 120 volt generator or a solar system together with a large and heavy battery bank to power them.  I have seen examples of DIY boat A/C using residential window mount room air conditioners but I am not sure they will stand up to the rigors of a marine environment.  I also worry about the stress the weight and leverage of typical window air conditioners would put on cabin bulkheads that were not designed for that kind of loading and about the effects of humidity in a marine environment on the electrical components.  The weight of an air conditioner is of more concern on smaller boats where the added weight  will be more noticeable and affect displacement and handling more than it would on a  larger yacht.

Evaporative coolers sometimes used on RVs (and land-based structures) aren't going to work well on boats.   Evaporative cooler depend on rapid evaporation of water so they work best in dry climates.  They work very well on RVs used for desert camping but since boats are sitting in the water the humidity level in the air is usually pretty high and evaporative coolers only work well in low humidity.  Evaporative coolers only really work at a humidity of 50% or lower and work best below 25%.  Very unlikely to find humidity that low on a lake, river, or ocean.

Cooling fans.  Fans don't really cool, but by moving air they make you feel cooler by evaporating perspiration faster and carrying heat away from your body.  Sometimes fans can be used to remove hot air or bring in cooler air to make the interior more comfortable too.  Portable 12-volt and even self contained battery powered fans can be use in even the smallest of cabins to create a little air movement that can make a big difference in comfort.  Heck, even fanning your face with a hand fan or even a paper plate can help!  You can enhance the cooling affect of fans by spritzing your skin with water from a spray bottle.  However, any kind of evaporative cooling will be limited by the high humidity in most marine environments.  Spraying yourself with cool water when the humidity is already 90 or 100% may help cool you a little but you won't get the same evaporative cooling you would get at lower humidity.  Sprays or mist systems generally work well in desert climates but not so well near bodies of water or other places with high humidity.  Even so, the cool spray itself can feel pretty good.

Many smaller boat cabins lack any kind of heater.   Since boating is often a fair weather activity and weight is a serious factor for boats, it makes sense to leave off heavy fuel tanks and furnaces.  The human body generates about as much heat as a 100 watt bulb so just being in a small enclosed space (like the cabin on a daysailer) will usually result in the space warming up fairly quickly, especially if you have more people.  My wife and I usually find just the two us us keep the cabin of our Macgregor 25 sailboat comfortable on cool nights without any auxiliary heat.  I am sure we would need more heat if outside temperatures dropped near or below freezing.  I once had to open doors and windows of our home during winter temperatures in the teens in Utah when I had 20 or so people in my living room even with no heat on!  Cooking inside your boat will warm things up but you should never use a cooking stove just for heating and you must always provide sufficient ventilation.  Often the heat from cooking an evening meal together with body heat is sufficient if your boat isn't drafty.  If you regularly need yet more heat you should obtain an auxiliary heater that is approved for maritime applications.  If you have 120 volt power an electrical heater is an easy and usually cost effective way of warming things up.  Lacking electricity you will have to consider some kind of  marine rated fuel powered heater.  Alcohol is often recommended for marine applications because the liquid fuel does not explode and the fumes aren't heavier than air and won't accumulate in the bilge.  Propane heaters that use self-sealing disposable fuel cylinders might be an option but you will need to store extra cylinders somewhere outside the cabin.   See Safety Tips for Small Propane Bottles from Practical Sailor for more information.

Automotive heaters that run off engine coolant can assist in warming up an RV.  I even had one RV that used engine heat to pre-warm the hot water heater while driving.  However, since most boat motors use water from the outside for cooling, automotive type heaters that run off hot water from the cooling system are not practical for use on boats.  The coolant generally doesn't get hot enough to be very effective and the plumbing to support it would be overly complicated and add unwanted and unnecessary weight on a boat.

Hatches and portals should be appropriately positioned open or closed to help you maintain the desired cabin temperature.  On hot days you will want to keep things fairly open to allow ventilation to help with cooling.  On cold days you will usually want to keep things closed ("batten down the hatches") unless you are using some kind of heater or lights (lanterns) inside that could put off toxic fumes and consume oxygen, in which case it is essential to maintain adequate ventilation.  Open things link the companionway slide will allow a LOT of heat to escape, partially because of the large opening but also because of the location at the top of the cabin (remember:  heat rises!).

Since boating is usually a fair-weather activity, cooling is usually the most common problem to be solved.  Some days may start out cool, then get warmer as time passes.  Dressing in layers so you can strip down to a comfortable level as things warm up is a good practice.  You can also use spray bottle to create a mist to help cool your body.   As mentioned above, a wind scoop can often provide much needed air flow for cabin cooling.  The physical activity often required by a sailboat often helps keep sailors warm.  Sometimes engine heat from inboard motors will also provide additional comfort on power boats.  If you need more heat be sure to get a heater that is designed for indoor marine use.  Catalytic propane heaters used in cabins and campers might work, but be sure to maintain adequate ventilation and store the propane cylinders out in the cockpit or on the deck.

Stay warm and keep your cool!