how much foam?

[boating brad]

im not a mathmatician and i know by reading previous posts that there is some sort of formula for figuring out how much foam is enough, i dont know the original weight and the foam is soaked! all i can afford is two 16lb kits i ordered from the us composites link from a previous post. anyway im replacing foam in a 17ft dixie it has a six cyl 90 merc, will two kits keep it afloat?<br />any thoughts are greatly appreciated

 

[JasonJ]

Re: how much foam?

What you are looking to do is displace water. You want to displace enough water to come close to the weight of the fully rigged boat and its max passenger capacity, but often there isn't enough void space to equal that, so if you can at least get close to the weight of the boat itself. The obvious goal is for the boat to not sink. If it gets swamped, it should stay at the surface so you have something to cling to and have something far more visible than your bobbing body. <br /><br />Water weighs about 65 pounds per cubic foot, so look at how much your boat and motor weighs, and divide it by 65. That is roughly what cubic feet you want to shoot for. You then have to try and figure the cubic feet of the available space you have. You also want to look at other areas of the boat, a lot of time they foamed up under the gunnels and other areas, and that does count. I would say in your case, get the two kits, and start your foaming at the transom and work your way forward. Your weight is at the back of the boat, so you want your boyancy around the engine so the boat stays relatively level if it gets swamped. Good luck....and post pics.

 

[boating brad]

Re: how much foam?

thanks jason, i dont know the weight but im guessing its no more than 1000lbs. so 16 should be plenty. <br /><br />i dont have a digital camera but if there is another way to get pic's out i will.

 

[Link]

Re: how much foam?

catfish: Use a regular camera then scan in the pic <br />Jason: I just did a comment on: Project Skanky Beast about an hour ago. My project is a (old now) river sled. Bought it new in 1990 when I was selling them. But have added so much weight to it that I'm going to have to add a lot of foam. My wife is a mathmatician and we think we have it figured out but your advice here is so simple I printed it out! Anyway as I said in my reply I'm new here. I've sanded, acid etched, primered, and painted it. Its now ready to be put back together. But before I do that we are going to do a sink test after I've added the extra foam! I'm thinking that the people here might like to see pics from bare hull to finished paint and the sink test? Then fully rigged and back on the water! I have a friend who owns a yard out here and is going to loan me the steel to tie on the boat in the right areas IE: 300 lbs where the OB sits.. 100 pounds where dual batteries go.. more in the live well.. 50 lbs on the front for the anchore etc What do you think? If not here just email from my earlier post<br /><br />Happy Boating<br />Link

 

[ajp]

Re: how much foam?

No big deal but I don't think water weighs 65lb per cubic foot, as was stated above.<br /><br />More like 10-15 -1 gallon of water is about 8 lbs.

 

[vegard]

Re: how much foam?

water DOES way about 62-65 pounds per foot (varies with temp and depth). I should know because I work at the University of Maryland's Neutral Buoyancy laboratory.

 

[iRich]

Re: how much foam?

yep, there is approximately 7.5 gallons of water in a cubic foot and it weighs 62.4 pounds. that is fresh water.<br /><br />Rich

 

[ajp]

Re: how much foam?

I stand corrected.