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post #11 of 26 Old 03-30-2013 Thread Starter
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Re: Increasing flotation

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Originally Posted by capta View Post
I don't believe floatation inside the hull would do anything to solve your problem. If you wanted to spend a small to mid-sized fortune in changing the boat to solve the problem, then you might try "micro-ballons" which are used by many racing boats to slightly alter trim and sailing characteristics.
A much cheaper and easier way to solve your problem might be to shift things around inside the boat (add an anchor and chain forward, stow heavier items forward; lighter stuff aft, etc.) until you have achieved the trim you desire.
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Foam heavier than air, fill voids (air) with foam to add floatation, I'm not seeing it.
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Originally Posted by msmith10 View Post
Capta is correct in saying that adding foam inside won't alter the lines, in fact it would actually worsen it by adding more weight in the area where you actually want more displacement. Move weight forward .
I might be incorrect in asking about flotation. It might be buoyancy that I'm looking for advice on. I am looking for ways to keep the stern up when it is loaded down with crew, gear, etc.
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post #12 of 26 Old 03-30-2013 Thread Starter
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Re: Increasing flotation

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Originally Posted by deniseO30 View Post
Don't motor so fast. Sail more. I think you WILL notice a difference! Displacement hulls drop lower in the stern when being pushed near hull speed.
Has nothing to do with motoring. The boat sits the same regardless of whether I am sailing or motoring. Other Neptune owners have told me of the same problem with their's. Just seems to be a lack of flotation/buoyancy in the stern.
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post #13 of 26 Old 03-30-2013
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Re: Increasing flotation

Looks like it was designed with short (or low) freeboard. It looks like it's low by design





Draft (max.) 3.50' / 1.07m Draft (min.) 2.00' / 0.61m
Disp. 3200 lbs./ 1452 kgs. Ballast: 1200 lbs. / 544 kgs.
SA/Disp.: 16.92 Bal./Disp.: 37.47% Disp./Len.: 154.2

Suggest taking the trailer to a scale.. then the boat and trailer. Do some some simple math. Only way is to lighten the boat or it's contents. Also, when you get the boat "lighter" May have more heel when sailing.

Adding a longer stern (sugar scoop) could help but then you would be getting into design issues.

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Last edited by deniseO30; 03-30-2013 at 05:06 PM.
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post #14 of 26 Old 03-30-2013
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Re: Increasing flotation

Foam on the inside will do nothing. In order to have it float higher - weight, outboard and all else equal - you will need to displace more water for the weight. So, in reality, you want more volume for the same weight. In essense a bigger beach ball to float the same amount of weight better. In reality; less weight at the rear or a boat with a bigger rear to support that weight.
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post #15 of 26 Old 03-30-2013
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Re: Increasing flotation

There is only one time that adding foam to the inside is going to make any difference and that is if the boat is totally awash...then it will float a little bit higher...but in that case you probably won't notice...

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post #16 of 26 Old 03-30-2013
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Re: Increasing flotation

Random thoughts, maybe posted a couple of days early:

It's not 1 April yet ... even in New Zealand. Actually, I'll assume the original post was perfectly serious, but somehow it seems too good an opportunity to waste, so here goes, in a spirit of fun and warm fuzziness:

You don't have your 300-lb. brother-in-law standing on the transom swim ladder, do you?

The builder didn't put the lead in the rudder instead of in the keel, did he?

You could get a tiller extension, sit further forward in the cockpit, and make the crew sit high side by the mast and hike!

Do your class rules allow trim tabs, hydrofoils, and jet engines?

Or, back to the spirit of April 1st, tie lots of helium balloons to your transom -- about twenty weather balloons might make a difference, though not so great for work to windward.
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post #17 of 26 Old 03-31-2013
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Re: Increasing flotation

Put the foam on the outside of the hull. Job done.

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post #18 of 26 Old 03-31-2013
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Re: Increasing flotation

Adding anything inside boat will increase the weight which will cause immersion rather than floatation. Those foams will aid floatation when the boat sinks. Move everything possible to the head. Or change the design of the boat so that the rear is more wider or deeper.
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post #19 of 26 Old 03-31-2013
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Re: Increasing flotation

"My outboard is a Honda 8HP, so no excess weight there,"
Unless it was designed to carry a lightweight 2-stroke, and you've got a 4-stroke, or similar problem.
Matt, it really sounds like you don't have a clue how displacement and bouyancy work. There's really no way to do what you want to do. It really sounds like you're perceiving a problem that doesn't exist, or a problem that is intrinsic to the design, especially if this is known to be common in these boats.

And if the problem is in the design, it goes back to "see above" regarding displacement and design issues. Get rid of the boat and get one that suits you better, because the alternative will be custom rebuilding your hull.
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post #20 of 26 Old 03-31-2013
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Re: Increasing flotation

I installed under each lazzerette, a tank. on the port side is a 50 gallon fuel tank, and on the sartboard is a 50 gallon water tank. I don't use them. I keep 'em there for buoyancy. They are there for long term back country trips only. I can slip out to the wilderness and protected water areas for a long time. The fuel tank was put for when i eventually put in an engine. Untill then it will remain empty. For ballance so will the water tank. I allready have a 65 gallon tank under the v-bearth, which is built in to the hull like a crash bulkhead. For general sailing and off shore they stay empty. I just assume they will keep the stern up in an emergancy. Maybe I'll pop up quicker or go down slower. I lost all that storage, but. I don't really have much crap on board. And all the carp I used to store there was just that, crap. It would turn into crap after a while anyway's from corrosion and not being used due to innacceasability. How many times did I clean those things out and find long lost items. Also don't store any thing that I do have above the water line on deck or inside the boat. I have bout 500 pounds of lead pigs I can use as moveable ballast in the bildge. All of my crap is stored low. I challenge every one to take every thing on board above the water line down to the tooth brush, and caculate it's collective weight. You may be surprised. A few courses in stability, like I took in My Tankerman, and then 200 ton capt. lisence, spawned my obbsession with keeping a low tansverse meta center.

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