*****HOW MUCH FOAM DO I NEED*****

[Jim]

Thanks to Brine for the Link! :beer:

This is a guide for foam in a boat. This is Federal law for boat builders. For those that think that they want to rip it out to make room or save weight or whatever.....think twice before doing it. TinBoats.net takes no responsibility with what you do. You are on your own. I recommend you leave it in and or replace what you remove.

https://www.uscgboating.org/regulations/boatbuilder_s_handbook/flotation_part1_e.aspx

 

[Bigkat650]

Great link Jim!

Details on what is legally needed; formula's to calculate the foam required; and examples of the formulas in use. Should be a big help to all those looking to replace or install foam, and for those who "don't think its necessary", it specifies this is a legal requirement--meaning God forbid anyone is injured or killed as a result of a boat not have flotation--the owner might be held liable.

 

[Dockside85]

Wow, pretty crazy when you do the math. A full 8'x4'x.5" sheet of closed cell foam from HD or Lowes is only 1.3 cubic feet of flotation material. That doesn't seem like a lot when removing the foam from 1 bench you take out can be a 3 or 4 cubic foot loss right there! But then again, most of our boats won't need the 25 cubic feet the inboard/outdrive in the example needed!

 

[fool4fish1226]

Thanks to Brine for the Link! :beer:

This is a guide for foam in a boat. This is Federal law for boat builders. For those that think that they want to rip it out to make room or save weight or whatever.....think twice before doing it. TinBoats.net takes no responsibility with what you do. You are on your own. I recommend you leave it in and or replace what you remove.

https://www.uscgboating.org/regulations/boatbuilder_s_handbook/flotation_part1_e.aspx

Jim I hope this ok to post here? Here is a link to the place I purchased my foam (https://www.uscomposites.com/foam.html). I used the 80lb kit (2lb foam) and used almost every bit of it on my build, I think I should be good

 

[Dockside85]

Man you didn't spare any expense on that 80lb kit! Stuff looks awesome though. I'll try that out on my next build.

 

[PSG-1]

Thanks for that link. Excellent resource! =D> Very technical, but a little basic math can help determine whether you've got enough foam.

They give an example, although, they give it for a fiberglass boat. That doesn't help those of us with aluminum boats. We need an example for that. So, if y'all don't mind me posting this.....here ya go:



Here's what I came up with for my jetboat, which is a modified 1648 Duracraft.
DISCLAIMER: This is a rough guess-timate, your particular application may be different, but this should at least give everyone an idea:




Step 1: Determine the flotation needed to support the submerged boat (Fb).
Formula:
Fb =([Wh x K] + [Wd x K]+ .69We ) ÷ B
Where:
Fb = flotation needed
Wh = dry weight of hull (425 lbs for Duracraft 1648)
Wd = dry weight of deck and superstructure (75 lbs for flooring, rear deck)

We = dry weight of factory installed equipment, hardware and accessories (50 lbs for console, cables and wires)


K = conversion factor for material used. See Table 4.1 below
B = buoyancy of one cubic foot of flotation material expressed in pounds.

Since the total weight for aluminum is multiplied by .33.....I added up the weight of everything, did the conversion, and arrived at (284 lbs)



Step 2: Determine the flotation material needed to support the submerged propulsion equipment (Fp).
Formula:
Fp = G ÷ B
Where:
G = 75% of the installed weight of the engine, drive and battery (inboard), or the engine, outdrive and battery (sterndrive) - in pounds to the nearest whole number;

(320 lbs total...this accounts for 75% of the weight of the engine, battery, and jet pump)


Step 3: Determine the flotation material needed to support the persons capacity (Fc).
Formula:
Fc = .25 (C) ÷ B
Where:
C = Maximum weight capacity. ( 3 persons @ 150 lbs or 450 total)


B = Buoyancy of 1 cu.ft. of flotation material used in pounds.


(112 lbs total)



Step 4: Determine the total flotation material needed (F) to support the boat. This is the sum of steps 1, 2, and 3 above.
Formula:
F = Fb + Fp + Fc



So, I added up the 112 lbs for persons, 320 lbs for the engine, and the 284 lbs for the hull, etc...and then divided that total number by 60 (buoyancy of foam per cubic foot) and arrived at a figure of 11.933...that's the amount of cubic feet of foam required....roughly.


Then, knowing that a 4x8 sheet of 1.5" foamboard is about 3.9 cubic feet, and that my floor is about 4x8, along with the 2 gunwales at roughly 2x8', (totalling up for another 4x8' sheet), that's 2 sheets of foam, or roughly 7.8 cubic feet.

I have another cubic foot of foam in the stern, and then about 2-3 more cubic feet in the bow...for a rough estimate of somewhere between 11 and 12 cubic feet of foam all together.

So, I have the minimal amount required, but at least now after doing the math and figuring it out, I feel a lot better about that boat's seaworthiness!

Again, thanks for posting that link, definitely clarifies everything.

 

[BloodStone]

Well...Considering that my current Aluminum project had zero foam on the floors/sides & I only removed one bench seat (& it only had 3-4 big junks of Styrofoam & the rest pebbles-what a pain in the arse those pebbles are); I think I'll be in fine shape. Especially when I add 1.5" on the floor & 3/4" on the sides & up in front as well. Added up, it is a lot more than what I took out.

 

[tla100]

Would the pourable foam help seal up and small leaks ?

Looks like some sweet stuff.

 

[jr1053]

Yesterday recovered my completely submerged(tied to dock on one side and the bow) starcraft mariner 180 after I removed the foam and discarded it while replacing the floor last winter. Shining example that foam does serve a purpose. swamped would have been a lot easier to deal with than sunk with the motor 8 feet under water.

 

[peabody]

im still confused... ive a 16 foot wood boat ... and i need to put foam in it ? its the law ?
i was wanting to keep the boat open.. where to add the foam ?

 

[highgeardaddy]

Has anyone checked with the contractors who are spraying foam as residential/commercial building insulation to see if they can provide the good closed cell stuff? I guess it really doesnt matter, the price just for the material on that DIY link is outrageous.

Are there any other options? I've had no luck with the foam sheets from HDepot or Lowes. It gets waterlogged quick then your packing around dead weight AND you arent getting any floatation benefit.

 

[highgeardaddy]

im still confused... ive a 16 foot wood boat ... and i need to put foam in it ? its the law ?
i was wanting to keep the boat open.. where to add the foam ?

I'm not an attorney but manufacuturers are (and have been for many years) held to the foam requirements. The information is provided here for reference. Someone in the know would have to advise on the legal stuff.

Note the Black Pearl was made of wood and it went to Davey Jones locker when it was loaded with booty. Its all about weight of water displaced by materials (net bouancy).

 

[Action762]

Hey Guys,

Ok so I am just curious if it is "required" by law to have floatation in your boat to keep it afloat. Who’s checking? I am looking to modify a 12' V and put a deck on it. There is not much room now as it sits. I was looking to put a low deck and seats with a high, "short", deck for the trl-motor. I have read through the forum posts here and I get it, but who’s checking? If you have floatation in your boat to keep it afloat if sunk great. It makes it easier to retrieve, if not buy some scuba gear and get it off the bottom. I am law enforcement so by no means am I trying to break the law or even bend it. I am just trying to learn because I am new to the whole thing, (i.e. first boat) and would hate to make a mistake and have to fix one like this. Thanks or clarifying if anyone does.

 

[txnman69]

glad i read this posting section. i'm currently doing a 14' aliminum boat mod. and cut out a section of each of the 3 benches (to put battery in one, onboard cooler/livewell in another and small storage in the other) made carpeted bench tops (middle one lifts up for access) , in doing so i removed ALL the styrofoam.
like other posts i've read here, my boat only had chunks of foam and most were rotted so bad i didn't recognize them as styrofoam.
my idea is to seal off the open sections i've made (for battery...etc) and use the expandable foam in a can from home depot or lowes.
if anyone can let me know , will this be enough floatation ? , what other options are there ? (BUDGET is a HUGE issue ).
thanks to all for any insight or tips

 

[fiberglass]

Jim is right about the manufacture of the boat has to put foam in a boat that is 21 feet or less. Its uo to you to decide how much foam you want to put back in the boat. I would prbally advise on putting back what you removed. On a aluminum boat what I would do different once I take out the old foam I would coat the aluminum with an epoxy before putting the new foam back in as to prevent the aluminum form oxidizing. No matter what foam you use it if it stays wet long enough it will soak up the water. I know the 2lb foam will typically expand about 20 to 30 times it liquid volume and of coarse that varies due to the humidity. Hope this helps a little. Thanks

 

[bassboy1]

No matter what foam you use it if it stays wet long enough it will soak up the water.

Let's echo this point one more time, as it is commonly misunderstood. Just because a foam is closed cell does not mean it won't soak up water. It most definitely will.

 

[txnman69]

Thank you fiberglass for your input , any is GREATLY appreciated not only by my self but all im sure

 

[apsauce]

Anyone else completely confused?? Maybe its just me lol but this whole foam thing has me in a headlock. Getting ready to mod my 12 ft 66 murry jon and this foam situation has smoke coming outta my ears lol.

 

[MiPikeGuy]

apsauce » 03 Mar 2013, 22:33[/url]"]Anyone else completely confused?? Maybe its just me lol but this whole foam thing has me in a headlock. Getting ready to mod my 12 ft 66 murry jon and this foam situation has smoke coming outta my ears lol.

I'm also confused, so you're not alone.

 

[txnman69]

hey guys, I modified my benches (14ft alumiline I think) made carpeted 3 piece bench tops and cut out the center section of the bench top and removed the foam (still leaving foam on both sides), the center sections of the benches lift up (on a piano hinge) , the front bench is small storage (extra glasses, scale, small baits...etc, ) the center bench contains my battery for trolling motor and fish finder, and the rear bench contains lifejackets,
I did replace all the foam during this process with new foam as the old foam was less than useless. My fishin buddy(not a small guy ) and I have encountered some scary waves for a boat like mine and came out ok ( gotta steer into it before hand !).
I haven't taken pics to post on here but will if it will give some help to those wanting to do the same type of thing.
hope this helps guys