need design help for home made pontoon style boat

[jimbo84]

ladies and gentlemen, after a few beers last night my buddy and i decided we would like to build a home made pontoon style boat, or perhaps like a bardge. the genious behind this idea is that we would like to build it with a bar and stools on the platform. now we r capable of constructing stuff but r in no way engineers. nor do we know much about flotation design. we would like to stay away from the barrel approch as we dont find it to be sexy. we would like it to sit fairly low in the water to hide the floatation devices under it as much as possible. (possibly making holes in the floor so if waves hit water can drain through) we were wondering if it possible to construct this using styrofoam or perhaps using pvc tubing plugged at both ends. it would have to support the weight of 4-5 guys (or preferably me and a bunch of chicks!) plus the bar (shouldnt be too heavy) this will be a slow moving marine vehicle as we plan on using like a 9.9hp motor on it. we were thinking roughly 9' wide and were wanting to make the platfoarm a hexagonal shape.
can anyone help us design such a watercraft? and tell us how to make it float? we would keep u guys posted with pictures and build updates. this is a winter project we were hoping to finish for next summers partying at the beach!

any help would be much appreciated!
thanks for taking the time to read our post.
Jimbo and Big Kevin

[gonzo]

Just get a pontoon boat and build a bar on the deck.

[jimbo84]

Originally Posted by gonzo

Just get a pontoon boat and build a bar on the deck.

where would be the fun and origionality in that?....

[alan white]

I don't know if putting a bar and bar stools on a barge is actually genius (requiring an IQ of 135 or greater), maybe only brilliant, but what really matters is how you design and build the hull.
First, you calculate how much the boat and a full load of people and equipment weigh. Then you'll need to design in some reserve buoyancy (How much more weight would actually sink the boat?).
Generally, the weight to sink the boat is equal to twice the loaded boat's weight.
The part of the boat that encloses air, if sealed, would also contain twice the boat's loaded weight in water, which, if fresh, weighs 62 lbs per cubic foot.
Usually, that enclosed air is located in the hulls, and it can be foam instead or in addition to air in case a hull is breached.
You can also design air chambers into seats and other places just as long as you arrive at the desired cubic flotation capacity.
A barge not intended to be a speed demon is probably the simplest boat to design. At low speeds, shape matters less, though you don't want to end up with a pig either.
Two cylindrical aluminum pontoons are the usual way to build a pontoon boat but a lot of different materials will also do. Plywood, glassed foam, steel, aluminum, and fiberglass all have pros and cons. Decide which material will work for you considering your abilities and finances.
You're not going to be drinking aboard, are you?
Just kidding...

[PAR]

Eager builders is the first step, now that the beer has worn off, you need to begin you search for a suitable hull design. I can tell you up front, if the hexagonal hull shape is a requirement, you'll probably not get too many serious answers, as this is simply because this isn't a shape that will be easy to propel. On the other hand if you want a really simple project, shaped like a boat with a bar in the middle, back, front or side, then there are several here that could draw one up that will not drown you or your 5 girlfriends.

You could have a barge type hull with a sort of hexagonal looking deck cap attached, though it would be for sitting mostly, not a deck. At this point you need to define what you need more, such as length, beam, draft, target speed, you target load is about a ton, where will it be used, how will it be used, general budget, will it be trailered and in general anything and everything you can think of in regard to the use of the party barge.

Alan, drinking aboard is mandatory, other wise we'd have to get married and hope death will come quickly and quietly in the night.

[cthippo]

Originally Posted by PAR

Alan, drinking aboard is mandatory, other wise we'd have to get married and hope death will come quickly and quietly in the night.

Crap, I guess I'm screwed then. I'm single and don't drink

EDIT:

How about round?

I can't tell you how long I've been waiting for an opportunity to post this pic on this forum

EDIT AGAIN:

I wonder if he isn't talking about hexagonal pontoons. Personally, I think pentagonal would be better since it gives you a flat mating surface (Wait, that came out wrong) and a keel chine in one shape. I wouldn't want to do the joining, but cutting the parts out would be easy.

Hexagonal could also be an asymmetrical hexagon like a rectangle with pointy ends.

[jimbo84]

alright boys, now were talkin dirty! we r not dead set on the hexagonal shaper deck, and we actually did think about a pentagonal shape. the way i see it, once we have gotten the pontoon and frame made, we can put pretty much any type of deck on top of it right?. now, we came across a sit that told us that styrofoam will hold 60lbs per cubic foot. we did a test of this with some foam i had at work and it did not work, however we think this is because it wasnt the right foam for this application (wrong density) we are gonna try the blue foam used to insulate foundations next. im assuming that we would have to fiberglass the styrafoam right? is this extra weight gonna affect floatation? i beleive that ur estimation of about a ton is probably corect (4 guys-800lbs and platfoarm with bar-maybe 1000lbs) so if we find the right foam we were thinking of 2 pontoons that would be 2'x2'x12' tappered up at the front. giving us roughly 5000lbs of floatation. i was thinking maybe something like this guys design http://www.youtube.com/watch?v=T4RudTL458Y
as for speed, we r not planning on going fast. prolly jus put a 15hp or smaller on the back. (if u go too fast we will spill our beers!)
all input is appreciated even if u think its dumb. we have never built anything like this before so we jus might overlook the dumbest thing!
cheers!

p.s. cthippo if we could build something like that pic u put up, we would have a party boat and a half! complete with danse floor and everythimg! lol

[alan white]

Foam can almost be considered air in terms of weight per unit of volume, at least when estimating. It only weighs a few lbs per cu ft on average and it displaces 62 lbs of water at least.
Your square pontoon sizes sound about right, though I'd suggest longer and maybe shorter in height (16"h x 24"w x 16' long). You keep your 5000 lb volume for a loaded max of 2500 lbs, allowing 1700 lbs for the boat, motor, and furnishings.
It's pretty easy to build plywood hulls to those dimensions using 1/2' plywood and bulkhead frames every 16-24" or so. The bows can be curved both in plan view and profile, which is all the shape you need, starting about 36" aft of the stems.
I envision chine logs and sheer longitudinals of 2" x 3"s epoxy glued and nailed together with hot-dipped galvanized roofing nails, and epoxy/glass taped at the seams with the hull undersidess to halfway up fully glassed for abrasion resistance.

[jimbo84]

kinda a newbie with some of these terms lol. any drawrings or sketches would certainly help!

[Dirteater]

The more I think about this, it sounds like "tubing" down the red river. you know...
8 tubes tide together and one in the middle for the cooler! *great fun*
hense, perhaps a sunkin "living room" kind of set up. It would be Octo-shaped, with beverages in the middle.
or.. perhaps I should go have a drink and think this through more.
I'm sure we all look forward to seeing the finished product! (invites? *L*)

[alan white]

Originally Posted by jimbo84

kinda a newbie with some of these terms lol. any drawrings or sketches would certainly help!

There are all kinds of websites with definitions to ponder. I can't currently use my scanner so you will have to concentrate very hard and have a few more beers. What terms don't you understand?

[cthippo]

Originally Posted by jimbo84

cthippo if we could build something like that pic u put up, we would have a party boat and a half! complete with danse floor and everythimg! lol

The same designer also built a yacht to that same style for the Russian royal family. I'll see if I can find a pic of it.

EDIT: There you go!
http://en.wikipedia.org/wiki/Livadia_(yacht,_1880)

Originally Posted by Dirteater

I'm sure we all look forward to seeing the finished product! (invites? *L*)

I'm only coming if the promised scantily clad females are present. On the plus side, I can be the designated driver.

[PAR]

I can tell you how horrible that shape would be, but suffice it to say it's about the worst. Again, reconsider the hex or round hull. Now you still could have these shapes, just don't put them in the water if you want to propel it with something more reasonable then a small atomic reactor. A barge or pontoon hull with a hex or round deck perhaps.

[Knut Sand]

Here's probably a bar.... (and an elevator...).

http://www.digit.no/wip4/lea-isadora...46&uiid=118565

Built by a retired farmer...

Vid to be found of this project here (and two others...): http://www.nrk.no/nett-tv/indeks/71999/

[Submarine Tom]

I think an aircraft survival raft would be ideal!

-Tom