Steel is hard, cold, dirty, heavy, difficult, and noisy to work. It is also cheap, available everywhere in the world, incredibly strong so hard to damage (when you build to “stout,” not “theoretically strong enough” scantling sizes) but easy to repair if you do damage it, easy to find skilled labor to repair it anywhere in the world, easy and fast to learn the basics of working, requires only a modest investment in tools to build with, and probably has the best resale value for a home made or custom professional built boat of any material. Except perhaps aluminum, which is far more costly so is at best, a “wash.” These qualities far out-shadow the bad side, and steel, with the right choice of design, is an ideal choice for a “one -off,” what a custom built boat is called, both for home-building or to hire built.
Any shape can be built of steel. One of the most beautiful steel objects ever built is an E-Type Jag; one of the most graceless, although of course it doesn’t have to be, is a typical gravel barge. My friend Darold Brekke could probably shape up a Jag body. Most people can’t.
If you want to home build in steel it’s essential that you understand the nature of steel. I’m saying this because while I have very little metal working experience and at this writing do not know how to weld, I have spent a lot of time around steel boat construction and have had numerous absolute beginners build from my designs. Watching them, listening to their experiences, and of course watching and talking with pros, I’ve made some observations about what appears to work smoothly for amateur steel boat building. So while the following ideas certainly aren’t carved in stone, they will, if you follow them, make your project go easier.
Every pro builder I’ve ever talked to says that any idiot can learn how to weld in just a couple months. I still don’t know how but I haven’t tried yet either. I’m going to learn one of these days. Ideally, the easiest way to go about it is if there’s Junior College in your town that offers classes. If there isn’t, you can still learn how but it will be a bit more hassle.
First, you need to buy the equipment. Get good stuff. Go to a decent welding supply store, tell the people what you want to do, and get what they suggest. Saving a few bucks and buying a low end tool of any kind is a dumb thing to do; get good tools. Wire feed systems make the neatest welds but cost more, are heavier and more awkward to carry around the boat, and need shelter from bad weather. “Stick” systems are the least expensive and most forgiving, but, they require a bit more skill to work neatly. All pros I talk to tell me that stick isn’t that hard to learn, and many “old time” pros tell me stick is the way for an amateur to go.
Which would I get? I dunno; decide for yourself!
If there’s no trade school near you you’ll have to teach yourself how to do it. However, this is possible. The welding store you buy your equipment from will have books; for instance, the company that makes Lincoln Welders has some fine “how to” info.
Even the smallest community will have somebody with a welding shop of some sort or another. I would find a local welder, and offer him 100 bucks to come by and get you started. Buy some scrap steel and have the guy show you how to weld it together.
After you feel comfortable doing that, and this will likely be a couple hours, you can start the boat.
Since you still don’t know what you’re doing, I suggest you start off by making the frames. These are straight line pieces, just welded at the chines, and will be easy. You can also make the deck beams and weld them on, but I wouldn’t. Doing that requires perfectly fair “setup,” and most home builders aren’t accurate enough in their lofting and setup to do that. It’s best to erect the frames, wrap a batten around the hull at the sheer, sight it to be sure it’s “fair,” adjust it to make it “fair,” and then weld on the deck beams.
How do you cut the steel?
There’s several ways. The “normal” is simply burning it with a torch. That works good but is hard to do very smoothly.
A metal cutting blade in a “sawsall” or “skillsaw” works OK but is slow; what works better for straight cuts anyway is a high quality “chop” saw with a good metal blade in it. One of the slickest things I’ve seen is a gadget that attaches to the cutting torch (see photo). It’s powered by electricity, has wheels, and allows you to burn out pieces as smoothly as a skill saw cutting wood. It costs around $300 and I’d buy one.
After the frames are made you’re probably semi-comfortable welding. Now do the keel.
The keel has long welds in it. You do NOT simply weld a continuous line. If you do that, you build up all sorts of stresses and at the least the keel will warp and at the worst it will blow apart later. Instead, like with any long seam, you weld 6” here, then 6” there, skipping around from side to side and place to place. You “tack” it together then “skip weld” around until you got it. Read a welding book for the proper sequence.
New steel comes with what’s called “mill scale” on the surface. This normally is removed by sand blasting before you can paint the finished boat. Sand blasting is a lot of work. You can hire it done, but it isn’t all that inexpensive to have somebody show up with the equipment. To avoid this, many people buy “wheel abraded pre-primed” steel. That way, all you need to do is spot blast the welded seams which you can do with cheap equipment, or grind down the welds, something you can easily do yourself.
I tend to think I’d use pre-primed material. However, here’s what some people don’t like about it.
This pre-primed stuff costs a bit more, although less than the added cost of hiring the sand blasting. But more important, some people worry that you don’t know exactly how well the prep work was done. It’s said by some that the quality of the “wheel abraded pre-primed” steel depends on how recently the “beaters” that scrub off the surface were replaced. People who worry about that say if you get a bunch of steel that was shipped off just at the end of the life of the wheels that do the scrubbing, well, you won’t get a good job. I dunno.
The next objection you hear is that the incredible new coatings require bare steel to really be effective. There’s new chemicals that turn rust to some sort of benign gray something or another that you can simply paint over. There’s even a new paint that the makers say doesn’t require sandblasting, the claim being it attaches well to mill scale and thoroughly binds it to the steel, and I’ve talked to some pretty knowledgeable folks who say it actually does the job; they use it inside the hull but still blast the outside.
Do these new coatings REALLY work? Who knows; probably, actually.
So these days I think while I’m sure these new chemicals work fine, I’d likely, myself, use pre-primed. It seems a lot simpler for a backyard builder or small shop to deal with.
What would I paint the hull with? I dunno. There’s new chemicals and resins appearing almost daily. When I had the metal work about done, I would start asking steel suppliers what they suggest. By the time I’ve written this I know there will be new products available I haven’t heard of.
If you look at construction plans for steel designs, you’ll notice two distinct building philosophies; heavy, or light. Steel is very strong, and also heavy. To save weight or to keep the center of gravity of the hull low, many designers spec out scantlings that are just stout enough to do the job, based on purely theoretic calculations of stress and load.
I disagree with this approach because light material is harder to work than heavy material, load factors are simply different than calculations can figure (such as hitting a log at night at 7 knots, striking the hull between the longitudinals; is there a calculation that figures how fast will you sink if you’ve used 1/8” plate to how many times you’ll wish you used 3/16” before you drowned? Lets call it, say, the “how long can you tread water” coefficient….) and, corrosion must always be considered. Today’s coatings are wonderful, but, steel can rust away as much as 1/16” in a year. I believe 1/8” plate is to thin for anything except perhaps a house wall and even then, it better be very low, or, backed up with a good structure behind it. I believe 1/8” is way to light for hull plate, and would rather have a plywood hull, which is stronger than steel for the weight, than an 1/8” steel hull.
Rather than a very light construction plan made up of many small pieces, I prefer a simple and heavy construction plan. Heavy frames and deck beams are less likely to distort when welding. 3/16” is the minimum plate thickness that will flow smoothly around the hull without tending to wrinkle. To see what I mean, wrap some tissue paper into a cone. Wrap a sheet of typing paper into a cone. The heavier paper is much easier to “control” the bend. Of course this all depends on what kind of boat you’re building and in some cases a low CG (center of gravity) is very important. But rarely is it important for a cruising boat. In fact, I know one large trawler yacht that had such an abrupt motion because of its low CG that the owner attached lead weights to the roof to RAISE the CG! I think he would have been better off with heavier plating on the hull and deck, but it was to late for that.
Like every other form of construction, steel boats are built differently in each region of the country. Our southern states tend to build them lighter than here in the Northwest, because use in the Gulf rarely strains them as much as can happen off the Pacific coast. Fine boats are built in the south, of course! But the typical Gulf shrimp boat isn’t as heavily built as an Alaskan crab boat. On my designs weight is rarely an issue, so if I err in my scantlings it’s always on the side of caution!
This gets us to the subject of the Drawn Waterline. This line is given the major significance in many quarters. Don’t get me wrong; floating near the “marks,” especially floating right side UP near the marks, is important! However, in “real” life the DWL doesn’t mean a damned thing. What this WL (what the DWL is more commonly called these days) is, is, a totally arbitrary line drawn by the designer, showing where he thinks the boat looks best floating. All the weight and satiability calculations and coefficients and whatnot are figured from this line. People worry about the line, and want to know how much ballast it will take to get to that line.
The answer depends on what kind of boat it is.
Take a rowboat or canoe. On the plans, there sits the boat floating on its WL. But in REAL life, it will NEVER sit there. The little boat when empty barely submerges. With 4 fat guys in it there might be just 3” of freeboard. Float on ITS waterline? NEVER! The same is the case with a cruising boat.
My friend Smitty, after loading his 54’ motorsailor down with 1500 gallons of fuel and all the miscellaneous junk he wanted for a two year cruise to Pogo Pogo, had his boat floating 6” below the DWL. This isn’t unusual; I doubt there was ever a cruising boat that didn’t float below its designed water line when fully provisioned because there’s a number of tons of consumables added in, and, you want the boat to be ballasted enough to stay right side up when the stores and fuel are low. That means it will float deeper than its WL when heading out on a trip. One way a designer can compensate for this is to give the topsides some good flair. Aside from looking good, it makes the hull volume get wider each inch it settles, making it harder to sink it any more.
Here’s an example of how that can work………
The 48’ Diesel Duck has about 36,000 of steel in her. By the time you finish her, the weight will be creeping up so that in normal running condition, she’ll we close to her 50,613 pound displacement. But as you load her, the harder she is to sink. If you were getting ready to cruise to Pogo Pogo and really loading her down, she’ll start sinking past the DWL. But not much. It takes 3.74 TONS to sink her 3” past her DWL. It takes around 6 TONS to sink her 6” past.
The ONLY boats that are meant to float on a designed waterline are race boats. In this case, especially with class race boats, things are very carefully figured around the WL. In fact small ones when at anchor will float bow down so that when there is crew in the cockpit, the boat will float on its DWL (designed water line).
This vagueness is very hard for some people to cope with, especially those with engineering degrees; them folks in particular, as a group, just can’t stand vagueness. I actually made an exception and refunded a guy’s plan purchase (all plans are sold as non-refundable, regardless of the designer) because he did a weight calculation after my weight calculation and discovered the boat he wanted to build would float several inches below this arbitrary DWL when fully provisioned. My reply of “so what?” didn’t wash with him, and rather than try to explain what I just did above, I gave him his money back and went fishing. Some things just aren’t worth arguing about……
I like a heavy box keel. Many builders assemble the bottom frames to a point, and then use a 1” plate keel. That works well, but, I like a steel hull that has a box keel and stems like a wood boat. I think it looks better, and, it gives a solid base for the hull to sit on when hauled out or beached. Some people even compartment it off and use it as a fresh water cooling reservoir. I personally don’t like that and suggest heavy wall split pipe welded to the outside of the keel instead.
On sailboats and larger powerboats, the box keel will be quite deep near the stern, making it very difficult to reach inside to back weld the sides to the bottom. This solved by making the sides in two halves, joined where the shaft pipe runs. You can reach about 2 1/2’ to 3’ into the keel, and building it like I’ve described here will allow you to reach all parts of the keel bottom.
Frames and Deck Beams:
It’s debatable how important frames actually are in steel hulls. Some builders don’t use any, relying on bulkheads to hold the shape. Probably because of my wood boat background, I spec frames at even station spacings, usually 3’ to 3 1/2’ apart. I have seen one builder who erects one or two major bulkheads, then, sets up wood forms on the steel keel, hangs longitudinals to the forms, welds the plate on, then removes the forms. This works, but doesn’t look right to me. Besides, the frames make building the interior easier because you have attachment points. And, if you come down hard on a rock, a big frame will make it harder to dent in the hull.
Flat bar frames are normally used in boats under 80 foot or so. The problem is that flat bar, especially when you have smaller pieces or big boat frames, tends to be rather wobbly. An “L” shaped frame (angle iron) is far more rigid. There’s two problems here. The stock material angle sections are harder to find in the type of dimensions you’d normally want for your frames. And, the top will be facing the hull sides which makes it impossible to sand blast underneath the top. If you want to use “L” section frames, in the “old days” you would first sand blast and prime them before you plate the hull. Or use pre-blasted and primed material. Of course today you also have the option of using one of the new chemicals that are supposed to do what sand blasting does. An angle iron frame in big boats might make sense because the angle frames are less floppy. I don’t know if I’d use it though.
Right now is where you need to start thinking ahead to make things easier for yourself.
One of the problems with hull materials except wood is that they condensate, so unless you insulate, you’ll be miserable inside. Steel is no different. There’s all sorts of types of insulation with the best being blown in. This has to TOTALLY cover the steel or it will drip. A common mistake is to insulate flush with the deck beams, which ain’t good enough; you need to COVER everything.
I strongly suggest, before assembling and erecting the frames or deck beams, that you take the pieces to a drill press and drill a series of 11/32” holes, maybe 10” apart, about 1” from the inboard edge of the frame or deck beam. This will make it very easy to bolt, with 5/16” galvanized carriage bolts, a wood strip to the frame. This strip will extend 1/2” past the frame or deck beam, should be say 1” x 2 1/2”, and the foam insulation will be blown in so that it covers the plate and frames and is flush, at the frames, with the outer edge of the wood strip. Then, you can easily attach a hull liner, such as 1/2” cedar, to the wood, with common ring nails. Plan on these strips at least as far down as the waterline, or chine, which is normally past the waterline. There’s no real need to insulate much past the waterline. Use pressure treated wood for these strips. Some people “shoot” the strips with one of those guns that can shoot nails into steel. This is faster than bolting, but the “nails” aren’t as heavy as the bolts and they won’t be galvanized. If you do it that way I suggest epoxying the strips to the frames too. Some people just use epoxy to hold the strips in but I would never rely on that. Today’s glues are marvelous but they’re even better when backed up with a bolt……
While I’m mentioning these strips, I believe before foaming the interior I’d stand up any major wood bulkheads. These will be important structural things for holding the interior in, so I’d want them securely bolted to the frames. I’d use MDO double side plywood, I’d epoxy coat the area touching the steel, and I’d still bed or put a piece of tar paper, between the plywood and where it lays against the steel frame. Attach fairing strips on each side of the bulkhead. They give a guide to how deep you blow in the foam.
Now then. The frames in my designs (and most “west coast” built boats) are not meant to have the plate welded to them. While the hull lines are “faired” via computer and are very accurate, steel plate is rigid stuff and wants to bend in its own fashion.
The idea is that the frames are stood up, then, a wood batten, say 3/4” x 1”, is wrapped around the frames about in the position the construction plan shows the hull longs (longitudinals) running. The exact position doesn’t matter at all. I like to see longs roughly a foot to no more than 16” apart. Run the batten, mark the frames where the batten hits, “nip” out a slot for the long at each point.
The “longs” wrap around the hull and are your fairing points. To get a really “fair” hull, as I said, the plate isn’t welded to the frames at all. Instead, the “longs” are lightly tacked to every other frame, the plate is hung and then the longs are moved out to meet the plate wherever the plate doesn’t touch them. Ideally you’ll have two or three plates per side and bottom (depending on the boat’s length, of course).
Bending these longs can be a bitch because the average rectangular section, 1/4” x 1 1/2” or so, simply doesn’t want to bend “fair.” Ship construction and some yacht builders uses angle or “T” section for the longs and that works for pleasures boats but it has some disadvantages to balance against how easy they bend. These are: you can’t sandblast behind the “L” or “T” shape so again, I’d pre-blast the piece. Unless of course, you’re using pre-blasted and primed steel. You have to cut a hell of a notch in the frame for the angle iron to fit in, and I don’t like that although of course you can weld a patch over the big notch. But the biggie that bothers me is that to get a really “fair” hull, the plate will rarely want to exactly lay on the frames. That means the longs, if they are set into the frames, won’t touch the plate unless you bang and force the plate against the frames, and that’s to much hassle. It seems better to weld the plate at the sheer and the chine, and let the surface between those points bulge out as it may want to, then, from inside, let the longs out to touch the plate. So while the flat bar is harder to actually bend around the hull, it’s easier to heat and move out to the plate, and, it requires less of a cutout from the frame. So I’d likely use flat bar for the longs in the type of boats that most of us are building. BUT, angle bends smoother than flat bar and if you have hull lines that you are positive are “conically developed” allowing the plate to really follow the frame shapes, the “L” or “T” longs will work fine. Make a scale model, say 1 1/2” to the foot, to see…….
After you erect the frames and tack in the longs, you do the plate. Now here is where I would probably hire a guy who knows what he’s doing to help. The material is heavy and doesn’t want to go where you want it to go. Somebody experienced with steel helping you is well worth a few hundred bucks.
Plating should be done with as long of plates as you can get; ideally two a side and bottom although three is more likely. The reason you use as few plates as possible is because that makes a “fairer” hull; hulls built as I’m describing come out looking as smooth as plywood, without bondo finishing, either.
After the frames, and the chine bar if used, and the sheer pipe are in, make a plywood pattern of the side and bottom. 1/8” door skin is the easiest but it’s delicate. 1/4” plywood is less apt to break, in large sizes like we’re dealing with.
While I’d make the pattern to fit along the keel, I’d leave the top several inches or more higher than the sheer. The sheer line is very important that it be “fair” and the consensus among the pros is that it is better to plate the hull, then go back, wrap a batten around the sheer marks, and burn it out to the line. That guarantees you’ll get a smoothly flowing sheer line.
Along this line, you see many people who stand up the frames with the deck beams already attached to them. This works as long as your lay-out and set-up is perfect, but, like with wood boats, it seems it’s a better chance of getting a “fair” sheer if you just stand up the frames, wrap a batten (and I’d use a piece of flat-bar, say 1/8” x 3” around the frames at the sheer marks, and site it. If it isn’t “fair” that shift the batten where you need to and make it “fair.” Then weld in the deck beams.
Some people don’t use any chine bar, just letting the side and bottom meet and then welding them together. The advantage of this method is that there is just one weld at the chine, where with a bar, there’s two welds as each plate needs to be welded to the bar. Supposedly the advantage of a 1/2” or 1” sold bar chine is that the slight roundness makes the paint stay on easier than it does on a corner. Frankly, I don’t know if that concern makes sense because 1) you’ll grind down the weld so will be smoothing the edge over, and 2) the new paints, like “ceram-coat” apparently are very hard to make wear off. If I was building, the appeal and simplicity of one weld at the chine would seem pretty appealing, I think. If you do use a chine bar, use SOLID bar, not pipe.
Make the patterns to whatever size you’re going to plate with. If you’re using three plates per side or bottom than make three patterns. Lay the pattern on your plate, trace it, then burn it to shape.
Now, here’s where I get away from “normal” procedure but, it works. One of my builders, an absolute ace welder who thought I was full of crap on this, tried it to prove me wrong. He wrote and told me he was shocked how much easier what I said was, and here is a prime example how, when you don’t know what you’re doing, simply thinking about what makes sense and doing it usually is the right thing to do.
For some reason both wood and steel builders start plating (or planking) in the middle of the boat, which makes it a bitch to pull the plate into the bow and stern. I’ve always thought it makes more sense to attach the material AT the bow and stern, then bend it to the middle. This way, the plate flows like it wants. Don’t worry about if it hits the frames or not, that doesn’t matter. Lightly tack it to the bow, wrap it around the hull (use come-a-longs or whatever), and where it ends, weld it to the longs.
Go to the stern and do the same thing. If you’re using more than two plates, now attach the middle ones; there’s little bend here so they’ll be easier to pull into position.
Go inside the boat. The plate is flowing around the hull but likely not touching all the frames or longs. Ignore the frames; you don’t weld to them anyhow. But, if there’s a place where the plate isn’t touching the longs, release the longs from where they’re tacked to the frames and using heat, push them out to touch the plate. Now weld them to the plate with short welds every foot or so, and securely weld the longs back into the frames. If you do it this way, your hull plate will end up as smooth as a prom queen’s thighs.
You see, steel, like plywood, is self fairing. It WANTS to flow on so don’t fight it. Let the hull plate go onto the boat the way it wants to. Don’t think about the frames because all they’re for is to hold the longs.
When you build the boat, there are many places where things can be done in any number of ways. Especially, regarding the shaft log pipe.
I don’t spec out the engine for your boat because I don’t sell engines. Many different ones will work, and everybody uses what they like best or can afford. Each engine will require a different shaft and prop, determined by the HP, transmission reduction, and type of prop. Therefore, the size of the shaft log and the various stuffing boxes and packings can’t be specified either, other than I try to spec a shaft pipe, in steel designs, that is big enough to take what I assume will be the “average” shaft most of you will use.
Now, if you call a marine store, you’ll discover there are cutlass bearings and inner seals for each size shaft that have a variety of O.D. (outside diameter), and NONE of them will fit into any pipe size you can find. Wood builders normally simply buy a bronze outer bearing, have a cutlass bearing pressed in, and then bolt that to the keel.
Steel builders have to goof around a bit more. Since no standard pipe has an I.D. (inside diameter) that matches the O.D. of any bearing, you can’t just press the cutlass into the pipe shaft log unless of course you take it someplace where there’s a lathe and have it bored out to fit a cutlass.
The noraml and probably simplest way around this is to first decide what shaft size you need, then, make your shaft tube out of a pipe with a larger I.D. than the O.D. of the cutlass bearing the shaft requires. There are various epoxy compounds that are used for filling the gap; “Chockfast Orange” is a common one.
I’ve never worked with this stuff but I think if I was to do it, I’d install the inner stuffing box on the pipe by using a common “self aligning” style inboard speedboat system of heavy rubber hose, hose clamped to the stern tube, with the inside stuffing box hose clamped to that. Then, I’d run a wood dowel or a pipe or something, the same O.D. as the shaft, through the stern tube, longer than the stern tube. I’d slide the outside cutlass bearing over this rod, smear it good with “chockfast orange” or an equal, and slide it into the stern tube. The dowel will make the cutlass line up with the inside stuffing box.
Never working this stuff makes it hard for me to tell you how to do it. One concern is that you don’t want this goop to stick to well to the bearing because you will need to remove it some day. Perhaps the answer is to coat the bearing with wax before gooping it? I’m sure the directions will discuss that. Regardless, the important thing is that the cutlass is in align with the inside stuffing box, and the dowel, or the shaft for that matter instead of a dowel (the dowel is lighter weight so easier to handle) will guarantee the alignment is OK.
Once the cutlass is installed, drill the stern tube on each side and insert a stainless set screw into the cutlass to hold it in place. Actually, I’d drill the holes and tap in the threads BEFORE installing the cutlass, then, after it’s in, drill into the cutlass for the set screw. Do not drill clear through the outer case and into the rubber.
Many steel boats use normal brass walled cutlasses. Electrolysis doesn’t happen because the hull itself is zinced. This is normal. However, the normal brass housing, used either in steel or a cast bronze wood boat holder, does make a slight surface corrosion, making it harder to remove down the road. I don’t know how it works in the epoxy goop stuff. But to avoid this, I’ve been looking into it and have recently learned about NON-METALLIC bearings.
These cutlass bearings are made by several companies such as DURAMAX and MORSE, and are in a fiberglass housing. It’s claimed they last as well as the brass ones but are cheaper, and do not corrode at all, making them easier to remove. Like the brass ones, they come in 2 to 3 outside diameters to fit a variety of inside diameter pipe shaft logs. For instance, if you’re using a 2” I.D. pipe shaft log, you can buy a cutlass that will hold as small as a 1” shaft to as big as a 1 1/2” shaft. I tend to spec large I.D. shaft logs because that gives you more options. There’s no reason not to put a 3” I.D. shaft log in a boat with a larger shaft because that will give you some “meat” to the cutlass, which means it will last longer. And of course the “chockfast orange” or the like will fill the slop.
I recently examined a boat with an unusual engine installation consisting of a flex coupling and 2 universals in a drive line connected to the prop shaft. The advantage of this is the engine can sit lower, and, there is no vibration at all. In fact, the engine could even be off center! The owner claimed the engine could jump the mounts and lay on its side without disturbing the alignment!
I’ve taken this idea to its logical end on a new design, a 49’ DUCK. The engine on this boat is installed in the bow. The sole supports of the wheelhouse are fore and aft allowing a higher sole, giving full standing headroom below the house. The interior layout starches from the transom clear up to station 14’, where there is a major bulkhead. The engine room is in front of that. The wheelhouse is a bit further forward; the front wall is at station 14, and the dry stack will run up through the front of the house. I suppose a dry exhaust line could run below the sole and come up in the place shown on the other DUCKS, but I would likely look at a wet exhaust in this case; it’s simpler. Maybe even the “north sea” type, exiting the hull in the engine room? Like the rest of the boat this can be handled in many different ways so do what you think best. This is a good time to repeat the basic rule of boatbuilding, especially amateur boatbuilding, which is, and repeat after me; “nothin is carved in stone.” The point is, there is rarely a “wrong” way to do anything, boats have been built and systems have been installed in all sorts of different fashions, and you know what? They all seem to work. So do it in a manner that seems the thing to do to you. You might have a clearer picture of the situation than the designer…..
Ronnie Hanson in Michigan or Egypt or wherever it is he lives way away from the “coast” told me about a guy in his neighborhood who built a 65’ steel sailboat, and when he finished, he came up with a pretty slick way of transporting it.
Since the boat has a heavy steel keel, these guys weld on a couple axles from a semi truck junk yard. They put on air shocks and brakes, just like a real semi trailer. Then they weld a “third wheel” hitch, like a big RV uses, on the stem. The semi “tractor” can hitch on to this, and off you go to the water!
This works fine, is less expensive because you can hire a “gypo” trucker rather than a “boat transport company,” and, as long as the “trailer” (your boat and its wheels) meet D.O.T. standards for brakes and lights, is perfectly legal! Just don’t go under any overpasses…..