your opinions please, my houseboat idea

Hello everyone,
What a wonderful forum this is. I have built things but not that were intended to float. I want to build my own houseboat and have scanned my drawing. I would appreciate any advise about it. I wanted it to be overbuilt (strength and floatation), pontoons are 2' x 4' x 24'. Cabin exterior walls 2x6.
Do I expect to need a really large outboard, speed not optimum requirement.
Boat to weigh approx 5 tons. These pontoons would float 10 tons plus but of course I want a safety factor. Thank you even if I'm nuts.

 

The suggested powerplant would be a thruster type 15 hp Yamaha outboard or similar, which will push the houseboat to perhaps 5 knots max. This keeps the cost reasonable; if you desire electrical power from the same engine as you use for propulsion, I suggest a non-marine diesel inboard coupled to both 240v generator and a prop shaft. The diesel could be 15-20 hp. The marine diesel is more expensive than a land type and involves a raw water circuit. The better setup for a house boat would be a "keel cooler" instead of a radiator or a typical raw water intake/pump/output.
These can be found second hand (heavy duty 240 volt Onan or Kubota generators in the 20 hp range). It will be necessary to transfer power from the shaft between the engine and generator to a reversing transmission with a prop shaft to the side. Then you can back up and use a bigger prop for efficiency.
Using an outboard, you would still need another engine for electrical power; The outboard would cost at least $2500.00 by itself.
Using a single inboard engine allows a bigger prop, lower output speed, the engine can't be stolen, and a lower overall cost. Also, better fuel economy (diesel) for electrical generation and propulsion.
You would need to buy a tranny. You would also have to unbolt the generator from the engine and make a custom coupling which would incorporate a sprocket or pulley. The tranny would need a pulley or sprocket as well.

Alan

 

Current designs of this scale are available, which takes the guess work out of the necessary hydrodynamic elements for the effort.

If really interested in doing your own design, then think simple. One or two hulls instead of four, using three different shapes for example.

The first thing you should do is calculate, as accurately as you can, the weight of the structure, supplies, full tanks (all of them) and a full load of crew, guests and equipment that may ever be aboard. With this number, you now know what you need to support, which permits you to float where you intend and build economically, but still stoutly.

Over building, just to make it strong is an easy way to make things actually weaker. I know this sounds counter intitutive, but it's most often true. Take a simple beam, say 20' long, made of three 2x12's nailed together, with well staggered joints. Strong right? Nope, not really, it can can't even support it's own weight without considerable deflection. The same dimensions, yet made as a hollow plywood box beam, it supports it's own weight, weights a fraction of what the solid wood beam weighs and costs less too. This is a classic example of engineering principle, one taught in engineering 101 during the first week of college.

In other words build the structure to be as strong as you desire, but not unnecessarily heavy. Weight on a small boat (this is a small boat) is costly. It cost fuel to propel, degrades performance potential, requires extra energy and money to build and you gain very little.

With twin outboards, you really don't need a bow thruster, just helm experience operating twins, which can turn 360 degrees in its own length or hold station into a contrary current.

Here's an example of a houseboat of my design. One is built, another is under construction. It's lighter and stronger then a typical "manufactured" houseboat of similar accommodation, which translates into better performance, lower operating costs, a cheaper build and an easier build. I kept the hull real simple and only used one.

 

I do not understand why you would want to design a boat from scratch when there are perfectly good and proven designs available. It would be a terrible waste of time and money to go to that much effort and found you have overlooked something important that experienced designers would not.

Nor do I understand why you want to overbuild it. Why on earth would you use 2x6 for the cabin wall framing? It makes it heavy and expensive to build, and operate, and does not necessarily make it any safer. This is usually the way inexperienced designers respond to the unknowns. It is not recommended. You need to know what you are loads you are designing to, and how to meet those load requirements.

Par is right, there are good designs out there about this size, why reinvent the house boat? It is a false economy trying to save money on plans by "designing it yourself" and end up with an expensive mistake.

What I would do if I wanted to build a custom house boat like that (and I have the engineering background to design one from scratch-and I would not do it) is buy a set of plans for something about the size I want, and alter the cabin and interior layout to suit my desires. At least this way I would get a proven hull and sturdy base structure. Studying the plans will also give you a better idea on how they are built. Usually any major changes you can run past the designer and they will give you some guidance as to whether it was a good idea or not. There is really no reason to design it on your own, I would be surprised if you could not find plans for the construction method you want and about size you need.

You might also consider buying an older used one that is in seaworthy condition, and rebuilding it to the custom interior that you desire. That could actually be less expensive and less work than building from scratch. Just make sure the hull is sound and you should be good to go.

Good luck.

 

Par

I'd be interested in seeing more specifics on this project. Basic specs, construction method etc. Possible consideration for a future project.

Thnx.

Rick

 

Drop me an email or IM and we'll touch base on RYD-47 (design shown above).

 

RYD-47 looks impressive to me, i am a wood worker, but never tried a boat build. Would love to succeed at this one. jmarleau@lawmens.net

 

Belle is 50' LOD, 16' beam, displacing around 14 tons (light). Plywood over frames, double planked bottom (2x 1/2" ply), single layer topsides and deck structures. Composite main cabin roof and pilothouse roof, twin screws, mechanicals below the weather decks.

Of course this wouldn't be my recommendation as a first build.

 

Nice looking houseboat, Rick.

 

Definitely not for a first time DIY'er though!

 

only took a look now at the myboat1.pdf
wish it was my fload in that sunny southern climate
guess not all marinas might think the same tho

 

Par,

May I say your RYD 47 is a thing of beauty sir! I just had my heart broken by a photo-finish bidding war for an 87' sternwheeler on Ebay (I came in third....probably a far, far better outcome for my finances in the long run of course) Has she been built yet? If so, any pictures? Any thought of selling plans for her? How about a steel hull? I have recently acquired what I feel will be an ideal site for boat building....my very own 600' canal off a small, non-commercial, but navigable, river with 3 acres of dry land at the end a few miles inland from the Mississippi sound in south Alabama. The only fly in the ointment is there is one bridge between me and blue water with a minimum vertical clearance of about 25'....how tall is she as drawn, if I may ask?

 

Yes, RYD-47 has been built and a second is under construction. She could be built in metal (steel or aluminum) with revisions to the current plans, which are for sale. She has a bridge clearance of 25' 2" with the mast up and just over 19' with it lowered flat (tabernacle) on top of the pilothouse.

Contact me by email (click on my name) for additional information.