Trailerable Houseboats Continued (again)

Discussion in 'Boat Design' started by silentneko, May 10, 2023.

  1. silentneko
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    silentneko Senior Member

    I'm back at it, sorry if this is long and confusing. Well I never stopped thinking about this, and have been looking for a small warehouse to do a build. I may have found one, but I don't want to commit until I really decide on a direction to go. That said, today I want to discuss hulls. PLEASE do NOT suggest a pontoon or cat hull! I can't use them because of height issues, and want more stability in the wind, so it has to be a monohull of some form. Trailerable means max bean of 8.5ft, maybe 24ft max, and able to be towed with a half-ton easily.


    In previous discussions I was advised to build a barge or other flat bottomed hull. I don't want a barge because of the pounding issues. Let me state this will NOT be an ocean crossing boat, but it won't be on rivers and lakes either. We mostly boat along the coasts of Florida, so this boat will be for camping along the intracoastal, and island clusters around the state. With maybe an occasional river tossed in. That said, this boat will occasionally see some chop and weather. Nothing crazy, but it needs to be ok with pushing through up to 2ft chop (don't laugh, a 2ft chop can beat you up here), at slow speeds and be stable at rest. A sailboat will not work because of the draft needed, we will take shelter and fish in areas that may only have 2-3ft of water many times.


    I have been looking at various trailerable houseboats for a while. The older more desirable versions seem to be mostly V-hulls, which I would think could effect stability. These include Stuery, SeaCamper, Land and Sea, Cobia Mini Yatchs, Yukon Delta...


    [​IMG]Stuery HB , on Flickr


    [​IMG]Seacamper HB , on Flickr


    [​IMG]Cobia Mini Yatch , on Flickr


    I’m back to wondering, why not just convert an other moderate V hull. There are plenty of Cabin boats or Cuddy boats out there.


    [​IMG]Cuddy , on Flickr


    [​IMG]Cabin boat , on Flickr


    These boats already come set up for an outboard in most cases, so I wouldn’t need to convert. I know using a planning hull is not ideal for a slow cruiser, but we are ok sacrificing some efficiency for the ease of the build. This is the boat that got me thinking. It’s an old Welcraft that someone built a cuddy and small cabin on. We would want a larger, more aesthetically pleasing cabin obviously, but it shows promise to me.


    [​IMG]Welcraft mod , on Flickr


    So, Could I build an old hull like this, with a lightweight cabin, and achieve similar results to the old houseboats pictured above?


    Building a full hull right now is now something I want to undertake…..but…..I do plan on doing it once I retire in about 15 years. The reason for using an existing hull for now is the speed of the build, and insurability (I’m in Florida after all).
     
  2. silentneko
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    silentneko Senior Member

    This seemed like a hot topic a while back. I guess the interest here has waned.
     
  3. kapnD
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    kapnD Senior Member

    Weight will be an issue, the more amenities you add, the more water it would draw.
    I saw a Florida houseboat/cruiser with superstructure built entirely of aluminum tubing and hypalon. It was also on a Wellcraft hull, an Airslot,if I remember correctly.
    The owner was quite happy with it, except for chilly mornings. He claimed it weighed less after the conversion, so performed well, except for the increased windage.
     
  4. fallguy
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    fallguy Senior Member

    The main issue is simple. Those boats design displacement is generally not sufficient for a houseboat. Key word is generally.

    The fact that you want it to be trailerable is another factor that reduces displacement, generally, because the width of the boat and thus house is limited, and the weight of the house is constrained, for lack of a better word.

    If you have an outboard; the outboard leg must be in the water. This means the outboard must be a certain distance above the water and in general, the hull depth is limited. Then other things reduce displacement. The transom angle, deadrise, bow angle..

    What is worse is many of the boats pictured would also become more and more unstable if built up higher. They are not made for a higher house..

    And this is why for a houseboat, the hulls must be made in such a way that they are not unstable if built up, offer significant displacement for their length, etc.

    Look closely at Mertens G23 hull. I would not recommend you take it offshore, but it will help you understand the dynamics better.
     
  5. fallguy
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    fallguy Senior Member

    Another issue with hull conversion is the hull you purchase may already be pretty heavy. Many of these old hulls use up a lot of available displacement on the vessel weight and offer a bit more capacity for passengers. Then if you build a house; you have maxed out the hull.. Houseboat hulls used in freshwater are your best go to if you want to do a conversion.
     
  6. bajansailor
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    bajansailor Marine Surveyor

  7. silentneko
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    silentneko Senior Member

    I'm very weight conscious, but I believe these hulls will have more capacity then I will need. Once I strip out the heavier production interiors I think I could possibly keep the weight to within a few hundred pounds max. That's not including removing the heavier large outboard and replacing it with one not even half the size. I might be net neutral in the end. I'm not sure what I'll build with yet, either foam core, or lightweight okoume/meranti/Luan. Wall framing will either be 2x2 or laminated ply be pending on the final cabin shape.

    Thanks.
     
  8. silentneko
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    silentneko Senior Member

    The displacement of many these hulls I think would still suit my needs. Obviously I need to be fairly careful when choosing which hull I buy, hopefully nothing more then 12 degrees. Keep in mind the capacities on these hulls were quoted so they could still get up on plane when loaded, I will only be using it at slower speeds. I'll be removing the very heavy solid fiberglass interiors, and replacing it with lighter weight material, so I could be net neutral on the weight in the end.

    Being trailerable is not an issue. As noted and pictured above these types of boats have been around since the late 1950's, all under 8.5ft wide and 13.5ft tall. They fell out of favor with the go fast generations. Then when they started gaining traction again makers switched to pontoons because it's easier and cheaper. I'd go this route if I could, but it's not in the cards.

    I'm not sure what you are getting at with the outboard legs and transom angles. That is all calculated into the total displacement of a hull at rest, but that will all be recalculated when I do my COG calculations. Once I have the hull and strip it I'll do my arm movement calcs to balance out the cabin. Obviously any time you raise height you effect stability. My point in this post is the configuration of many hulls out there seem similar to the ones used for these smaller camper boats. So why not.

    I don't really want to bash him, being he recently died, but I would never buy/build another Jacques Mertens plan. I have several of his plans, and currently have an FS17. I found many errors, that if I didn't recheck them I would not have a well functioning boat. Worse then that is when he finally agreed the plans had major errors, he still wouldn't fix them. The GT23 contains similar errors. If I were going to build from scratch I would just design my own hull like I did for my last few boats. That is my plan a few years in the future, for now I just need a quick turn around so the family can have some fun.
     
  9. silentneko
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    silentneko Senior Member

    So I've actually looked at a few houseboats already. The problem is, even when they say "remodeled", they really need a lot more work. These were put together many years ago with cheaper resin technology (all old poly) and lots of wood.

    A great example is the Stuery rebuild on YouTube, from AYO Fishing. Now I don't agree with some of the work he's done, or the progression in which he's doing anything (motor and bracket before glass and paint is done?), but it shows how bad the issues can get.

    Doing my own conversion means I know it is done well and safely. Starting with a clean slate is easier and quicker then fixing others mistakes most times to me.

    So to answer the question, yes and no. I think I can buy an old hull, strip it to the stringers (maybe further) build a cheap lightweight cabin, and add a smaller (25-40hp) motor for $12-16k.
     
  10. fallguy
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    fallguy Senior Member

    I'm not pointing at the GT as a possible build; you misunderstand. I am pointing to it as a hullform that is suitable.

    I own the LB26 plan and felt it was missing some important information, so I never started; we digress.

    A battery bank with 400AH batteries weighs 260 pounds, an inverter and associated wiring another 50. Just 310 pounds, add a couple solar panels and you are over 400, just for the electrical to support a house. Can be done with half the stuff or lifepo4, but you are not accounting for a LOT.

    Most houseboats need freshwater if operating on salt or brackish. 50 gallons of water and plumbing is about 450 pounds.

    All of this adds up very quickly. You need a lot of immersion rating and a lot of displacement for a houseboat. The propane systems, stove and tanks another 50-100, depending upon the reserve.

    So, be warned, your vee hull must be very perfect for a houseboat conversion or won't work.

    The outboard leg. You don't understand? The outboard l/u must be lower than the hull. If you bury the hull 6" deep for added displacement; you bury the engine, too. Only so much immersion can be done. Most of the boats you show, I would estimate ppi at 500 pounds per inch. So, the hull sinks an inch for each 500 pounds extra. Passengers, say 4 a little over an inch. Water at 50 gallons and plumbing or less easily 500, another inch or more.

    The hull is really the most critical piece of the houseboat.

    Here is a too wide to trailer vee hull that is very full, wide sides, etc.

    A few of the hull pictures you shared would be way less displacement, even if this were narrower, based on the hull shape.


    IMG_0469.png
     
  11. silentneko
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    silentneko Senior Member

    You are making a lot of assumptions, and missing the point of this boat. A complex solar inverter system, huge batter banks, large water tanks.... This isn't a full time live aboard, it's a small house/camper boat. Made for weekends out, not months. I don't need a big bank of batteries, the ac and mini fridge will run off the generator. I don't need 50 gallons of water, 15-20 will be plenty, and the new fuel tank and water tank will be smaller then most of the stock fuel tanks many of these boats had. No propane system, just a small camper stove.

    I didn't mean I don't understand the running draft of an outboard. I meant I don't know why you are bringing it up because that obviously is accounted for and easily adjusted.

    I understand the hull is the most critical piece, that's said for any boat. The GT23 is a flawed hull, and not a great example. The Garvey style front doesn't lead to enough buoyancy, which is why those who built them have issues.

    The Gibson you posted is not in the realm of what we are talking about here. If memory serves they are about 10.5ft wide and 36ft long. They also have very tall and extremely heavy cabins and living space on the roof. The boat I'm looking for is near 20% narrower, but maybe 35+% shorter. So the ratio is actually better for lateral stability. It will have a lower profile and much lighter weight cabin.
     
  12. fallguy
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    fallguy Senior Member

    I read the thread title as trailerable houseboat, so assumptions get made absent details.

    Most 'houseboats' would be setup for 2-4 people and a weeklong cruise.
     
  13. silentneko
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    silentneko Senior Member

    Details were in the first post.

    "Trailerable means max bean of 8.5ft, maybe 24ft max, and able to be towed with a half-ton easily."

    "so this boat will be for camping along the intracoastal, and island clusters around the state. With maybe an occasional river tossed in."

    Week-long cruises are possible easily within my vision, but mostly a long weekend. We spent 3 days on the 18ft Hobo houseboat. Only used maybe 5 gallons of water, and 8 gallons or so of fuel I think.
     
  14. silentneko
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    silentneko Senior Member

    I love the Gibsons style too, but it's not meant to be moved over the road often. If they made a 8.5ft x 24ft version I'd be game.

    Yes, you can pick one of them up pretty cheap these days. Actually there have been some for free recently, but you'll need 25k+ to restore one to its prior glory.
     

  15. rberrey
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    rberrey Senior Member

    I know you said no sail boats , but B&B Yacht design sharpies are designed for your waters , bridges and draft . A new design which has already been built is Matthew Flinders 24' 6" scaled up 5% from 23'4" .
     
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