increasing bouyancy with a given hull size

[bowfisher8967]

I have a 14' jon boat that sits too low in the water in the back. Its got a 15hp merc which is the recommended max motor size for this boat. I've shifted every moveable item aside from myself and the motor to the bow and it still sits low. I saw a website that sells aluminum "pods" that you weld on to your transom to increase flotation with a heavy motor and to supposedly "get you on a plane faster." www.explorebeavertail.com/ Anyone have any experience with these, or with other methods for water displacement?

 

[oops!]

Re: increasing bouyancy with a given hull size

hi.....
welcome to iboats !

IF the boat has all weight removed....including rotted wood and wet foam.and still sits stern heavy....pods would be an exellent choice......many fiberglass hulls have pods moulded in.....and they work fantasticaly by adding displacement aft of the motor. this will help with getting on plane and also while sitting....as the bow wont be sticking up in the air.

i would look into why the boat is sitting stern down..

it could be a number of factors.....like wet foam under the seats !

hope that helps
cheers
oops

 

[metriccrescentwrench]

Re: increasing bouyancy with a given hull size

I'm waiting for someone to suggest adding foam inside the hull :facepalm:

Yes, some sort of pod or outrigger will help. Also agreed that you need to figure out why it's sitting low to begin with. It's always a possibility that it's just the weight of the engine.

How wide is the boat by the way?

 

[Texasmark]

Re: increasing bouyancy with a given hull size

Weight vs weight. The area of the hull displaces so many cubic inches of water. Water weighs about 7# per gallon (without looking it up) To support X # of rig you need to displace X # of water. Either increase the area/volume of the hull displacing water or remove the weight.

The addition of pods aft of the transom are an excellent way to do that as mentioned.

My 2c,
Mark

 

[Frank Acampora]

Re: increasing bouyancy with a given hull size

Old folks maxim: A pint weighs a pound the whole world round.

Water weighs 8 pounds per gallon. Salt water slightly more. However, for figuring displacement in a hull application it is handier to remember that a cubic foot of water weighs about 64 pounds.

Again, if adding pods, remember that at rest it is NOT the total size of the pod that counts, just the size that is under water. For example: If you add a one cubic foot pod but only half of it is under water (at rest) then you are only displacing 1/2 cubic foot of water and only adding 32 pounds of buoyancy. Once on plane, it is then the surface area of the pod in contact with the water and speed that determine lift

 

[smokeonthewater]

Re: increasing bouyancy with a given hull size

I think that in the long run you'll find out the the cheapest and best way to solve your problem is to find a wider/deeper hull

 

[Bob_VT]

Re: increasing bouyancy with a given hull size

Use the $300 plus installation money towards a bigger/wider boat. I would consider hull shopping before I considered modification

 

[Texasmark]

Re: increasing bouyancy with a given hull size

Agree with Smoke and Bob.

 

[etracer68]

Re: increasing bouyancy with a given hull size

I just seen this on CL, is this what you want?
http://milwaukee.craigslist.org/boa/2734214852.html

 

[smokeonthewater]

Re: increasing bouyancy with a given hull size

I just seen this on CL, is this what you want?
http://milwaukee.craigslist.org/boa/2734214852.html

WOW that's an ugly boat.... what were they thinking? lol

 

[V153]

Re: increasing bouyancy with a given hull size

Oh I dunno. Agree they ain't purty but I think the "beavertails" are kinda cool. Fill em with helium for a lil more bouyancy ...?

 

[jigngrub]

Re: increasing bouyancy with a given hull size

Something most people don't think about when considering this type of modification is the added stress on the transom, both in the water and out.

The advice to look for a bigger hull is your best advice.

 

[bowfisher8967]

Re: increasing bouyancy with a given hull size

metriccrescentwrench, my hull is 48" wide, and etracer that is exactly what i'm looking into.. I know its ugly but I'd be crazy enough to try it out. But as a few people suggested, it may be a little hard on the transom. My whole rig was only $500 or so, and the pods are expensive, though they sound like the best solution if i want to keep this hull. I dont know enough about steel welding much less aluminum, so maybe I can try to build these pods out of some strong but light-weight/pourous wood? (maybe an oximoron in itself). And fill them with insulation foam from HD, and then bolt my creations to the transom with L-brackets!!!! Any objections? (safety-related or otherwise). Going once...

 

[5150abf]

Re: increasing bouyancy with a given hull size

Building them out of wood will be heavy and filling them with foam will be even heavier, the best way to do it is with a hollow metal box but yes your idea will give you a bit more flotation until the wood gets water logged then it is a deficeit.

Your next problem would be attaching them to the hull, I don't think L brackets will hold the stress and once you rip out a couple screws below the water line you have a whole new set of problems.

Look for a newer bigger hull.

 

[Home Cookin']

Re: increasing bouyancy with a given hull size

maybe it's not "too low" but how it's supposed to be.
maybe you need to sit further forward. A tiller extension would be cheaper.
Is it "too low" on a plane or low speed? When you stand in the stern corner to dock or fish?

You might look for a replacement with higher freeboard. In fact if you are considering bolting a bunch of scrap lumber on it, why not just add top rails? does that solve the problem?

 

[lncoop]

Re: increasing bouyancy with a given hull size

WOW that's an ugly boat.... what were they thinking? lol

Come ride in one on the lower White River in January and you'll think it's the most gorgeous rig you've ever laid eyes on. My uncle has one like that with a fifty horse Tohatsu and I covet it greatly. Bowfisher, something doesn't add up. That 14x48 shouldn't even know the fifteen is back there.

 

[bowfisher8967]

Re: increasing bouyancy with a given hull size

maybe it's not "too low" but how it's supposed to be.
maybe you need to sit further forward. A tiller extension would be cheaper.
Is it "too low" on a plane or low speed? When you stand in the stern corner to dock or fish?

You might look for a replacement with higher freeboard. In fact if you are considering bolting a bunch of scrap lumber on it, why not just add top rails? does that solve the problem?

Its ok on a plane. Its when i'm sittin still or at the dock (especially when the launch ramp is downwind from the water. The waves almost splash inside!) I agree with incoop that something doesnt add up. Is it possible that when the boat was made (by Valco in the 70's) they assumed a lighter 2-stroke would be put on it? Were 4-strokes not as common then? Home Cookin, what do you mean by top rails? or was that a joke?

 

[smokeonthewater]

Re: increasing bouyancy with a given hull size

yeah... nobody had 4 strokes then....
I think H/C was talking about improvising a splash guard of some sort IE like maybe 1x4 lumber on edge forming a 'fence' around the stern


Incoop, on a river in january??? better have a heated wheelhouse if ya wanna impress me LOL

btw it's not just the boat, the float tanks, double jack plates, and whale tail all make a package deal for me..... odd design and 4 bandaids to make it work..... sorry If I offended ya tho

 

[cyclops2]

Re: increasing bouyancy with a given hull size

I have a16 foot Lowe short shaft ...15" high transom... but it is 65" wide at the rear area. I have had a 1986 30 hp Evinrude on it. Have to really be ready to pull up & turn into any waves.

Is your Jon boat a short shaft 15" transom. How much do you weigh ? My fishing buddy was 300 + -. Had to be carefull with him moving or leaning & the 30 hp motor. We only fished where we could WALK to shore.

 

[Home Cookin']

Re: increasing bouyancy with a given hull size

what you are describing is what 14' jon boats do. All normal. they just have their limitations. You just have to be careful back there. Never stern anchor.
We often have fatalities here when 2 or more guys try to go fishing in a 14', and both stand up in the stern to boat a fish.