How can I simplify my house boat design for easier construction?

Discussion in 'Boat Design' started by LandFish, Jun 22, 2021.

  1. mc_rash
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    mc_rash Junior Member

    In my eyes it's a nice project you worked out. I'm not sure wether it fits for (rough) seas or not but I have one aspect which might be an aspect to discuss. I would place the stove more in the middle of the length for better heat distribution.
  2. fallguy
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    fallguy Senior Member

    I have been on an uninsulated houseboat in 27F and it sux. Was last year actually. Propane use is high and the operator had to bring us tanks on Tuesday from a Saturday departure. My uncle was 93 and cold and unhappy in early September.

    The best insulation for a boat is rigid polystyrene. Two inches is 5cm and r10. Do a heat calc and 35cm is R70 which is overkill and not that much space available...boat real estate is pricey and 14" of ceiling is too much. You will have significant heat loss in windows. Also, a place like a salon/settee doesn't need high ceilings. Windows can be lower and shorter, less windage, less internal volume, less space to heat, less heat loss.

    Do a heat calc on the space. At some point, the windowed walls lose more heat than the ceiling and all the ceiling r value under the sun won't matter if you need 4000 btus to wall losses, an incremental 300 for another inch of ceiling becomes silly, etc.

    Happy mediums are the rule and R10 in a boat roof is way better than 0.

    I did a spreadsheet for the skoota.
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  3. clmanges
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    clmanges Senior Member

    If you can stand to lose a little headroom along the sides, you might consider building the cabin, or at least the upper part of it, in a semi-cylindrical shape. This would hold heat better and show lower resistance to side-winds.

    I haven't seen this done aside from some sampans and the like, so I suspect there's a downside to them I'm not aware of, aside from loss of storage space and the reduced headroom at the sides. Just an idea.
  4. comfisherman
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    comfisherman Senior Member

    Coastal Norway is one thing, Norwegian fjords are an entirely different thing. One can have spectacular storms, one has some of the most incredible protected waters on earth. Suffice to say I'm not going to comment on the required seaworthy nature and need of each individual voyage.

    I'll stick to general observations.

    The bow sections look like they could be better then a barge bow or a simple triangle bow like more budget pontoons. But enough better to rationalize extra build time is probably a wash.

    Camber takes a little time to build on roof and decks, but I've never seen a boat that didn't benefit from one. It doesn't take very much camber to shed unwanted water, a little on the roof will go a long way.

    I'd like to point out that rarely is the shell or hull the time consuming aspect of any boat build. Systems installation can suck up an immense amount of time if not properly thought out and designed. If it were me, I'd be focusing on going over the systems over and over again to optimize ease of install.
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  5. LandFish
    Joined: Jun 2021
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    Location: Norway

    LandFish Junior Member

    Thanks again for the good inputs!

    I was hoping to save some money by using conventional insulation like glass batts.
    However I see now that its kinda dumb to waste so much interior space on insulation when I can have the same insulation power with a thinner material.

    Great advice! Would you mind sharing your spreadsheet for the skoota?

    Good idea! I've moved the stove around quite a bit and still not satisfied with its current position.
    Putting it more in the middle would be better as you say.

    If this can help make the boat more sea-worthy it is definitely worth a try.

    Thanks for the insights! The ferry I posted pictures of is on river in a coastal town so its only protected by the buildings in the town.
    The last point is really something I will do. For me it is okay that the interior part will take a lot of time, I just want the hull to be made by qualified boat builders so that there is less risk involved.
  6. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    @LandFish are you able to send private messages through the Forum?

    I wanted to send you one, asking for your email address, so that I can email you some info that might be of interest, but I couldn't.

    If you can send a PM, can you send me your email address please?
  7. sharpii2
    Joined: May 2004
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    sharpii2 Senior Member

    I think it may be possible to make the pontoon style houseboat format more seaworthy, but the design compromises may not be very palatable. The following changes will likely be necessary:

    1.) the house is going to have to be significantly shorter than the hulls. I'd say no more than 60% as long. So, a 12m boat would have a house no longer than 7.2m.
    2.) most of this extra hull length would have to be in front of the house, say about 25% of the total length or more. So, this 12m boat would have at least 3m of hull in front of the house. The final 1.8m would be behind the house.
    3.) the hulls will have to have either deep "V" sections, or have long, shallow keels.

    As I hope you can see, your houseboat has now turned into a power catamaran. But at least now it will have a fighting chance when dealing with wind and wave.

    If you're not to greedy for speed, you could probably power this thing with two 30 hp outboards.
  8. LandFish
    Joined: Jun 2021
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    LandFish Junior Member

    I'm new to this forum and don't know how to send PMs, maybe you could share your info here?
    I am sure the info could be interesting for other people too.

    This is very helpful! I am going to make a drawing based on this to see if I could live with it.
    In Norway you need a special certificate to use a boat thats more than 50 ft. So I could maybe change the boat design so that it is just under 50 ft in order to get a bigger house on it.
    Maybe 15 meter long and then have a house on it that is 9 meter in length. That could potenitally work.
    Is it necessary to have a lot of space behind the house in terms of wind resistance?
    Also great that I won't need to have a lot of hp for this to work, it will help reduce costs.
  9. fallguy
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    fallguy Senior Member

    Another thing that increases stability is if the house is narrower than the hulls. Of all the houseboats I have been on, very few of them did not have walkable side decks. It certainly adds cost, but those locations are needed for shore tying ropes and make good storage for other things like a paddleboard or access to water heater or deck plate access to water, blackwater, etc.
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  10. bajansailor
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    bajansailor Marine Surveyor

    I was a bit hesitant about sharing the attached GA drawing on a public forum, as Alnmaritec had come up with this proposal (at my request) 10 years ago, when the St Vincent Govt were inviting proposals for a floating Ranger Station to be based in the Tobago Cays in the Grenadines.
    Sadly it all seemed to fizzle out - I am not sure if their Park Rangers (the Tobago Cays are designated as a National Park) ever did get a base in the end.

    The hull shape shown in the attached GA will be infinitely better than what you have shown in your initial proposal, but it still would not be much fun powering along to windward in this cat in rough conditions offshore.
    This hull shape is very similar to the hull form of the OSRV that Alnmaritec built for Barbados 11 years ago -
    ALN 096 ‘Responder 1’
    We took this OSRV out on sea trials in the North Sea in early April, and it was quite rough - she coped ok, but the seas encountered were more than what her design brief had specified, as she normally is just on stand by for potential oil spills in fairly calm coastal waters here.

    Nobody has yet dared to ask you what your budget is - this is always a thorny issue - so I will.
    A 15 metre house boat with a professionally built hull in Norway is going to cost quite a lot of money I think.
    And if you want to have reasonable rough water capability for going along the coast (ie outside of any 'sheltered' fjords), then I still think that you would be much better off in every way by simply purchasing a suitable second hand motor yacht that has proven sea keeping qualities.

    Attached Files:

  11. LandFish
    Joined: Jun 2021
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    LandFish Junior Member

    Thanks for sharing it anyway! Its interesting to see a design like this. The pontoons look really thick, like 1/3 of the width. How heavy would a boat like this be?

    You are right, budget is important to talk about. The main problem is that I don't know how much something like this costs.
    However I have roughly 175 000 USD available and I can probably borrow another 58 000 USD if necessary.
    I have looked into second hand yachts, but I am not a fan of their interiors, which is one of the reasons I want to try realizing my own design if possible.
    There is also always the possibility to have it produced in a cheaper country like Poland.

    Here is a new draft for a power catamaran houseboat. What do you guys think?
    I made it more similar in design to the ferry boats that I like.
    I am unsure about the pontoon shape. I am feeling like they should be much thicker at the end of the boat, is that right?
    15 meter length
    4 meter width
    3.8 meter height
    [​IMG] [​IMG] [​IMG] [​IMG]
  12. fallguy
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    fallguy Senior Member

    You won't want vees aft. You need displacement, wide and flat. Your cabin is too large. You need access to engines and an aft deck is nice anyhow. But things like engines need access. The way you drew it; she'd likely sink right to the deck.

    This is why designing is not a wise idea. Too complex for us amateurs.
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  13. bajansailor
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    bajansailor Marine Surveyor

    The design displacement of the Alnmaritec cat is 12 tonnes - yes, the hulls are 'thick' but they need to be in order to get the required volume of displacement to support the vessel.
    And that 12 tonnes adds up very quickly, even for aluminium construction, as the cost of being 'liveaboard' is high in terms of outfit equipment desired, and especially fuel and water capacity.
    Your deep vee hulls look rather sexy, but they are not going to have enough volume of displacement - you would probably find that the load waterline is perhaps halfway between the underside of the bridgedeck and the sheerline.
    Landfish, when I was a young lad I thought that designing boats was just like what you are doing above, except that we did not have CAD in those days. I went to college and quickly found out that the actual drawing part is only a tiny fraction of boat design - a lot of it is tedious weight estimates.
    And that is what you need to do.
    Not just tallying up all the weights on the vessel, but also their longitudinal and vertical positions as well. Longitudinal so that you can be confident that she won't trim excessively down by the bow or the stern, and vertically so that you can then get an idea as to what her stability will be like.
    Fallguy has nailed it very succintly above.

    Realistically, I would be very surprised if you could get just your hull built in Norway for less than US$175,000, never mind all the outfit items.
    The OSRV mentioned above cost approx GBP 300,000 10 years ago - and this was a basic boat, before all the oil spill recovery gear was added.

    What do you not like about their interiors? Is it the colours, or the styling, or the layout, or ???
    Colours and styles are easy enough to change.
    Buy a second hand Fairline, Princess or similar type of motor yacht around 35' - 40' long, and you should be able to live on board very happily, as well as having the capability of cruising along the coast, even in rougher conditions.
    Here are some typical examples -
    2002 Princess 40 Fly Power New and Used Boats for Sale -
    1997 Broom Ocean 38 Power New and Used Boats for Sale -
    2005 Prestige 36 Power New and Used Boats for Sale -

    Edit - a gentleman here built a power catamaran to his own design about 15 years ago. The hulls were very narrow, and he was very proud of their shape, telling everybody how seaworthy this boat would be. She was designed for carrying passengers along the coast on cruises, and she was launched just before Christmas, to great fanfare - the owner was looking forward to his first cruise (with bookings already) on the 26th December.
    And when she was launched, she just about floated with her deck awash, and nobody onboard - yet he was planning on carrying up to 40 people on this vessel.
    He never did any buoyancy or weight estimates - and neither did he take any notice of various people (including me) who told him before hand that he did not have enough buoyancy in his hulls - he knew better, but he had to find out the hard way.
    He quickly hauled the boat out, and set to with some major modifications to make the hulls much wider, and finally launched again about 6 months later.
  14. kerosene
    Joined: Jul 2006
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    kerosene Senior Member

    lots of windows are heavy and expensives, insulate badly and result in steamy greenhouse in the summer.

    My experience form tractors...
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  15. LandFish
    Joined: Jun 2021
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    Location: Norway

    LandFish Junior Member

    Thanks again for all the great feedback.

    I understand that there is a lot more to boat design than just the drawing part. And I would of course not build anything before I did a thorough calculation.

    I am the type of person that wants to explore all possible solutions before I jump ship and buy or build something. This is so that I can do an informed decision for my vision.
    Part of that is drawing up a concept of what I want so that I can get a price estimate on building it, but also to consider what kind of similar options exist on already built boats.

    My main problem about boat interiors is that I feel claustrophobic in their cramped interiors. I am also not a fan of the curved walls in boats. This might sound silly, but I want to feel like I'm in a house, not a boat. But still have the option of cruising my home to different town.
    I do appreciate the links though, it helps to see what other options there are out there!

    Thanks, I'll reduce the amount of windows.

    I was thinking outboard motors so that its not necessary for motor inspection inside. On this kind of boat that has space underneath deck, is where I think would be a good place for water tank and similar things.
    Isn't it enough to have cleats on the side of the boat for tying ropes? Or do cleats have to be upright on sidewalks for them to be effective?
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