Cheap/Durable Hull Material For Houseboat

[IATGC]

If you make 4x4' pontoons with a 12' beam, you have l_l l_l or 6 sheets ply and framing. If you make a monohull, you would have l____l which would use 5 sheets of ply and less framing. And better stability than a pontoon.


I don't think that's what's in creosote. If you soak the wood with diesel, you will smell it for as long as the boat lasts and it also makes it pretty flammable. Plus you can't glue to it. I've used good condition railroad ties for various things and they don't last all that long, ants and bugs don't seem to mind it much.

A 58' long boat, besides being very expensive, or not, needs a lot of engineering to counteract the various ways it can be stressed and broken apart.

You're right, that's a very good point. It would be much stronger and simpler to build/design a monohull, not to mention the extra carrying capacity. I had actually decided to start sketching a monohull design before you posted that ironically.

Are you familiar with a little houseboat design known as the Lisa B Good? Look at the framing schedule of this boat. It's very similar to the frame my much larger design will have.

http://www.duckworksbbs.com/plans/browne/lisa-b-good/Lisa B Good notes and drawings.pdf

Of course the frame in my larger boat will be much stouter, and slightly different. The longitudinal/bottom frames will be made out of doubled up bolted/glued 2x12x16 framing lumber. The cross members will be made of doubled up 2x6x12 framing lumber that is glued together. The plywood will be 3/4 MDO on the sides and bottom. It will have 17 oz glass cloth on the bottom, sides and fore/aft decks.

So with all this negativity surrounding creosote, does anyone know of a better rot or insect prevention treatment? Ethylene Glycol?

 

[gonzo]

You can buy treated wood at the lumber store. The scantlings look really heavy. Have you done a weight estimate?

 

[IATGC]

I would like to upload photos of what I have drawn so far to give everyone a better understanding of this design. My mobile phone isn't allowing me to upload anything.

I don't have a PC or laptop. I don't have a drafting table. I'm drawing this with an engineer's ruler and a large sheet of 1/8" graph paper. I'm no good at 3D drawings unless I use CAD programs.

Unfortunately this method of drawing doesn't allow me to draw very fine details. I need even larger paper.

And no Gonzo, I have not yet done a weight estimate. Are you suggesting that I make it lighter than this?

 

[IATGC]

I did a quick weight estimate for the bare hull and got these numbers based on what I have drawn so far:

Approx. 6500 lbs for framing

Approx. 2100lbs for 3/4 MDO hull sheathing

Approx. 850lbs for 1/2 plywood used for decks (includes interior flooring)

Approx. 250 lbs for enough fiberglass cloth and epoxy/resin to cover the sum beach

Approx. 100lbs for fasteners


So 9800 lbs for bare hull, not including paint, rub rails, engine, miscellaneous stuff

Add another estimated 2500lbs for superstructure and 1000 lbs for engine. Furniture, passengers, pets, appliances, etc. would be another 1500 probably

That gives a total displacement of 14,800 lbs which would give a draft of approximately 4.5 inches if my calculations are correct. (Not including skegs or anything like that)

Water (fresh) weighs 62.4 lbs/ cubic foot

Hull displacement volume is about 672 cubic feet at 1' of draft. (Not including skegs or anything like that)

672x62.4 = 41,932.8 lbs

You can put a lot of stuff in this boat before it sinks a foot into the water

 

[IATGC]

I know that I made this thread about material choices, but would twin 25hp 4 stroke outboards be enough for this hull? Or should I just go with an inboard diesel around 50hp?

I'd rather not sacrifice the ability to go in extremely shallow water, that's why I ask if outboards are feasible

 

[ondarvr]

I'm thinking that for a 58' house boat you're way under on weight and cost, and while a pair of 25hp outboards will move it on a nice day, it may turn into an uncontrollable monster with a little wind and current. A mono hull would be harder to control than a pontoon boat.

 

[IATGC]

I'm thinking that for a 58' house boat you're way under on weight and cost, and while a pair of 25hp outboards will move it on a nice day, it may turn into an uncontrollable monster with a little wind and current. A mono hull would be harder to control than a pontoon boat.

While I agree with you on the motors not being enough for a vessel this size, how is the rest wrong?

My estimates (cost and weight) were for a bare hull without anything. No engines. No cabin. Nothing.

It is a basic barge hull built with fiberglassed MDO and a common lumber frame.

I can even give you the new materials list I have come up with based on my drawings.

I used real world prices and engineering tables for lumber weight...

Maybe you can tell me what is 'off' about it...


91- 2" x 6" x 12'. $1200 24 lbs apiece

40- 2" x 12" x 16'. $1400 64lbs apiece

20- 2" x 6" x 16'. $300 32lbs apiece

2- 2" x 12" x 12'. $45 48lbs apiece

36- 3/4" x 4' x 8' MDO. $2400 70lbs apiece

120- Square yards of 17oz fiberglass cloth. $1200 about 135lbs

20- Gallons of epoxy/resin. $1400 about 160 lbs

10- Gallons of excellent exterior grade glue. $500 about 90lbs

10- Gallons of rot prevention treatment (Ethylene Glycol?). $500 about 80lbs

21- 1/2" x 4' x 8' MDO. $1000 48lbs apiece

20- Gallons of bottom paint. $1000 about 160lbs

1000- Misc. Stainless fasteners. $500 about 200lbs



That's $11,445 for the floating bare hull, and 9835lbs by my calculations

On second thought, I should really add another longitudinal frame to the center. Lucky for me my design is incredibly simple, so this is easy.

That's an extra 800lbs (give or take with glue and fasteners and rot prevention treatment) and $385 for the lumber needed to do that. That would require 51 2" x 12" x 16' boards instead of 40, and the price for those would go from $1400 to $1785.

$11,830 would be the revised bare hull price with the extra longitudinal frame

10,635lbs would be the revised bare hull weight with the extra longitudinal frame

 

[ondarvr]

There are costs that you haven't included, do you have a building big enough to build this in, then a way to transport it to the water.
Building a boat from scratch is rarely the lowest cost method of getting on the water. why not buy an older one and renovate it, still not cheap, but quicker and lower in cost than building one yourself.

 

[IATGC]

That is an important part of the cost that I forgot to factor in.

So there's a 15,000 sq. ft. fenced equipment storage/commercial lot in Omaha, Nebraska. It is less than 2 miles from the Missouri river (where I will launch the boat).

It is around $750 per month for the whole thing. I think you can choose a section of it to use and they'll only charge you for that section.

When I have enough money to build this boat, my new full time job will become building the boat. Probably 8+ hours a day. I should be able to get it done in less than 6 months at that rate.

So let's estimate $9000 for a year of renting this ENTIRE lot, $2500 for a shelter to build under and $20,830 to completely build and install an engine in this boat. Might as well add another $2500 for a truck to move it to the water, and $1500 for a crane.

The total cost comes out to $36,330. I can cut that to $31,830 if I build it in 6 months.

It might be cheaper to simply buy a small lot to build it on. I'll have to look.

 

[IATGC]

So I satisfied my curiousity/cheapskate nature by looking at lots for sale in Omaha. There seems to be an abundance of 3-4000 sq. ft. lots that are around $5000 total cost. Most of them are within 2 miles of the Missouri river.

My monthly mortgage payment after buying one of these lots would be a princely sum of around $20. I don't know if I can afford that guys, I mean that's less than my phone bill...

I would probably put $1000 down on it. 1/5 of the way paid off if I did that.

The zoning might be a problem, I believe these small lots are meant for residential development only. I could tell them a white lie and say I'm building a mobile home. It is mobile. And it is a home.

That's a much better deal than $750 a month for that equipment storage lot.


So let's recalculate. My entire cost including a shelter for the boat ($2500), 12 months of mortgage + down payment ($1240), the complete boat ($20,830), hiring a large semi truck for a whole 2 miles ($2500), and hiring a mobile crane ($1500) would be $28,570.

As for that lot of land, I'd probably sell it after I paid if off.

Not to bad, eh?

 

[ondarvr]

By my quick estimate you'll have about 2,000 square feet of surface for the finished barge, but you have 1,216 listed

 

[IATGC]

By my quick estimate you'll have about 2,000 square feet of surface for the finished barge, but you have 1,216 listed

Not sure where I specifically listed 1216 square feet in my updated numbers.

The length is 56' without rub rails or "bumpers". Total length with the husky rub rails/bumpers would come to about 58'.

The beam is 12' without rub rails. It would come to 12' 6" with rub rails.

The hull depth is 3' the whole length, except for the ends. The bottom curves upward near the ends like a typical scow or barge.

56' divided by 8' is 7.

12' divided by 4' is 3.

21 sheets of 3/4" x 4' x 8' MDO for the bottom.

7 sheets of 3/4" x 4' x 8' MDO per side. 7x2 is 14.

I know this isn't exact, but it's pretty close to what is needed. Let's add an extra 2 sheets of plywood for the bottom just in case.

I come up with 37 sheets of plywood total for the hull, 1 more than my original estimate. Probably a good idea to add that extra one.

The bottom would mostly use full sheets of plywood. Let's just say it uses 23 sheets. That's 736 square feet for the bottom using this estimate.

However, this doesn't account for the fact that the sides don't use full sheets of plywood.

Each sheet of plywood on the side will start out as 3' x 8' and 24 square feet. There are 7 total per side. The bottoms curve upward like a typical scow or barge starting 8' from either end.

So 2 sheets per side will go from 24 square feet to about 18 square feet when accounting for the upward curvature.

That's 156 square feet per side, or 312 square feet of outside surface area for both sides.

746+312 is 1048 square feet for the exterior of the hull.

The inside of the hull won't be glassed, probably only coated with some sort of rot prevention treatment. It will be well ventilated.

To glass the fore and aft decks I would add another 180 square feet (or 20 square yards). I would probably just use polyester roof fabric for the decks because they aren't going to stay wet constantly.

 

[ondarvr]

You need to have a complete deck laid down and glassed before you remove it from your shelter, so you have an additional 700 square feet to account for. Plus all the supporting structure for the deck.

I don't round down, I round up slightly, I used 4' for the side height, so using 3' reduced my quick estimate a small amount.

You can't put an open bath tub in the river with exposed wood and leave it to sit unprotected in the elements.

I work with the very large houseboat builders, they use glass covered ply for some of the house structures, but not the hulls. And yes, rot is an issue even above the waterline on these boats.

 

[IATGC]

You're right, I wouldn't want an open bathtub. I was actually going to build the main cabin on the hull (40.5' x 11.5' x 6.5' interior dimensions) before I dismantled the shelter. It wouldn't exactly be an open bathtub.

I am considering maybe adding a smaller cabin (19.5' x 11.5' x 6.5' interior dimensions) above the main cabin. It would add 224 square feet bringing the total square footage to 690.

So does the cabin really need to be glassed? I feel like exterior grade plywood and a good coat of house paint would hold up just fine.

My main concern would be making the roof water tight since 98% of the water the cabin would see would be rain.

Edit:

I had originally accounted for 21 sheets of 1/2" x 4' x 8' MDO for the interior and exterior decks. I didn't include this in my square footage calculations for the hull exterior because I don't consider the deck to be the "exterior". Most of the deck will be inside the cabin, and it will be stained or varnished plywood.

The fore and aft decks will really be the only ones that need polyester roof fabric or fiberglass.

 

[ondarvr]

I wish you luck.