Do I need to add foam or other flotation?

aeviaanah · Sep 29, 2011

I just got the deck cut for my Alum. 12' Deep v. I have yet to cut in storage areas. Trying to think of the best combination. Should I leave an area open for foam only? How is the best way to figure the amount needed and placement?

Thanks.

Captain Ahab · Sep 30, 2011

You do not have to add foam - but just remember that if your boat gets swamped with water it will sink.

i opted for the no foam route but will likely add some next year. I do have two pumps - a battery operated and a huge hand pump

If you do add foam do a search here and know the difference between closed cell and open cell foam

aeviaanah · Sep 30, 2011

Captain Ahab said:
You do not have to add foam - but just remember that if your boat gets swamped with water it will sink.

i opted for the no foam route but will likely add some next year. I do have two pumps - a battery operated and a huge hand pump

If you do add foam do a search here and know the difference between closed cell and open cell foam

Thanks for the reply. How would you figure the best placement and how much foam that is needed?

Ranchero50 · Sep 30, 2011

You can search this site for lots of good threads on floatation. You can also do a Google search for the USCG boat builders handbook for the official recommendations.

Foam should cause a swamped boat to float level gunnels up. Too much foam in the bottom and it'll want to flip over on you.

Jamie

Hanr3 · Oct 2, 2011

If your boat sinks, what are you going to hold onto until help arrives?
If your boat sinks, what are the odds someone will see your head bobbing in the water?

Add floatation yesterday. The life you save may be your own.

aeviaanah · Oct 2, 2011

Hanr3 said:
If your boat sinks, what are you going to hold onto until help arrives?
If your boat sinks, what are the odds someone will see your head bobbing in the water?

Add floatation yesterday. The life you save may be your own.

Good point. I decided to dedicate a whole seat for flotation and around half of another seat. You think this will suffice?

Sawdust Farmer · Oct 2, 2011

aeviaanah said:
Hanr3 said:

If your boat sinks, what are you going to hold onto until help arrives?
If your boat sinks, what are the odds someone will see your head bobbing in the water?

Add floatation yesterday. The life you save may be your own.

Click to expand...

Good point. I decided to dedicate a whole seat for flotation and around half of another seat. You think this will suffice?

How much weight do you plan to have in the boat? Also, how balanced will it be?

sf

aeviaanah · Oct 2, 2011

Sawdust Farmer said:
aeviaanah said:

Hanr3 said:

If your boat sinks, what are you going to hold onto until help arrives?
If your boat sinks, what are the odds someone will see your head bobbing in the water?

Add floatation yesterday. The life you save may be your own.

Click to expand...

Good point. I decided to dedicate a whole seat for flotation and around half of another seat. You think this will suffice?

Click to expand...

How much weight do you plan to have in the boat? Also, how balanced will it be?

sf

motor 135
me and passenger 160 + 160= 320
accessories + deck = 100

Roughly 550-600 lbs. It will be balanced as best as possible. The hard part is the motor being so heavy along with me there to control it. It will be a bit stern heavy as I'm using the outboard, should be fairly balanced when fishing.

J.P. · Oct 3, 2011

1 liter of air=1 kg of boyancy. use this to estimate the volume of flotation you need. adjust accordingly depending on the density of the foam you are using.

you'd want your gunwales to float higher than the water if you want to be able to bail your boat out in the event of swamping. otherwise, you'd need to get towed all the way to shore before your boat floats again.

i don't use foam. what i do is fill my compartments with capped PET bottles. the're free, lightweight, i can remove them anytime if i really need storage space or when it's time for periodic inspection of the hatches. PET never rots. and best of all, i get to help save the environment by recycling plastic. the only thing i have to make sure of is my hatch covers are properly secured so the bottles do not float away.

Sawdust Farmer · Oct 3, 2011

J.P. said:
1 liter of air=1 kg of boyancy. use this to estimate the volume of flotation you need. adjust accordingly depending on the density of the foam you are using.

you'd want your gunwales to float higher than the water if you want to be able to bail your boat out in the event of swamping. otherwise, you'd need to get towed all the way to shore before your boat floats again.

i don't use foam. what i do is fill my compartments with capped PET bottles. the're free, lightweight, i can remove them anytime if i really need storage space or when it's time for periodic inspection of the hatches. PET never rots. and best of all, i get to help save the environment by recycling plastic. the only thing i have to make sure of is my hatch covers are properly secured so the bottles do not float away.

I never thought of doing that. As long as they are secured in place, that should work really well! =D>

sf

Jdholmes · Oct 3, 2011

I would think you would waste a lot of potential storage space filling it up with empty bottles to match the buoyancy of a closed cell foam...we are talking keeping 1000lbs + afloat. That is a lot of bottles.

I would rather place sheets of closed cell foam on the bottom and not lose my storage space.

aeviaanah · Oct 3, 2011

J.P. said:
1 liter of air=1 kg of boyancy. use this to estimate the volume of flotation you need. adjust accordingly depending on the density of the foam you are using.

you'd want your gunwales to float higher than the water if you want to be able to bail your boat out in the event of swamping. otherwise, you'd need to get towed all the way to shore before your boat floats again.

i don't use foam. what i do is fill my compartments with capped PET bottles. the're free, lightweight, i can remove them anytime if i really need storage space or when it's time for periodic inspection of the hatches. PET never rots. and best of all, i get to help save the environment by recycling plastic. the only thing i have to make sure of is my hatch covers are properly secured so the bottles do not float away.

Well 1000lb is about 450kilograms. By this do you mean I will need 450 liter bottles? Can you give me a rough estimate?

Hanr3 · Oct 3, 2011

Everyone remodeling a small boat should read this document. It is published by the US Coast Gaurd and specificaly addresses safety issues for the back yard boat builder. Numerous sections are on floatation, floatation location, caculations, etc. Its only 53 pages long.

https://files.dnr.state.mn.us/education_safety/safety/boatwater/backyardboatbuilders.pdf

If your more comfortable, google "How to figure small boat floatation" and this will be one of the links.

aeviaanah · Oct 3, 2011

Hanr3 said:
Everyone remodeling a small boat should read this document. It is published by the US Coast Gaurd and specificaly addresses safety issues for the back yard boat builder. Numerous sections are on floatation, floatation location, caculations, etc. Its only 53 pages long.

https://files.dnr.state.mn.us/education_safety/safety/boatwater/backyardboatbuilders.pdf

If your more comfortable, google "How to figure small boat floatation" and this will be one of the links.

Very good read Hanr3. Much appreciated!!

J.P. · Oct 3, 2011

Jdholmes said:
I would think you would waste a lot of potential storage space filling it up with empty bottles to match the buoyancy of a closed cell foam...we are talking keeping 1000lbs + afloat. That is a lot of bottles.

I would rather place sheets of closed cell foam on the bottom and not lose my storage space.

aeviaanah said:
Well 1000lb is about 450kilograms. By this do you mean I will need 450 liter bottles? Can you give me a rough estimate?

no offense, but i think you guys are forgetting to factor in the specific density of water. your 1000lb payload will not weight 1000lbs when you submerge it in water, thus you will need far less boyancy to keep it afloat. the article posted above supports this principle.

in theory, the same volume of foam will have roughly the equivalent amount of boyancy as the same volume of air (in a bottle). test it in a bucket and you will see what i mean.

i'm not trying to convince you because foam and bottles have pros and cons, we are free to choose whichever we are comfortable with. foam is really more efficient, that's why professionals use it. but since i am a diy person, i try to find cheap alternatives. a bunch of bottles will have space between them which will fill up with water, as opposed to foam which will be tightly packed. so effectively, the same compartment filled with foam will be more bouyant than if it had bottles inside. you can shape the foam to fit wherever you want to put it, but you can't do this with bottles. i do not need that much boyancy, so i can get away with this disadvantage. but just like most boaters, i appreciate extra storage space. but foam comes at a cost. because of this, i'm thinking of installing an alternative to my bottles. i intend to place thick plastic bags in smaler compartments, then blow the bag and seal the openings. the result will be an air bladder that conforms to whatever shape the compartment is. i am not yet comfortable with the idea because of the possibility of puncture, but i will do it once i see a suitable "bladder" material.

Hanr3 · Oct 3, 2011

J.P i am not yet comfortable with the idea because of the possibility of puncture said:
Tire inner tube. You can get them in just about any size, they conform to the space they are in, its thick rubber, repair kits are easy to come by and easy to do. On the down side, they do lose air over time, so you will have to inflate periodically.

aeviaanah · Oct 3, 2011

J.P. said:
Jdholmes said:

I would think you would waste a lot of potential storage space filling it up with empty bottles to match the buoyancy of a closed cell foam...we are talking keeping 1000lbs + afloat. That is a lot of bottles.

I would rather place sheets of closed cell foam on the bottom and not lose my storage space.

Click to expand...

aeviaanah said:

Well 1000lb is about 450kilograms. By this do you mean I will need 450 liter bottles? Can you give me a rough estimate?

Click to expand...

no offense, but i think you guys are forgetting to factor in the specific density of water. your 1000lb payload will not weight 1000lbs when you submerge it in water, thus you will need far less boyancy to keep it afloat. the article posted above supports this principle.

in theory, the same volume of foam will have roughly the equivalent amount of boyancy as the same volume of air (in a bottle). test it in a bucket and you will see what i mean.

i'm not trying to convince you because foam and bottles have pros and cons, we are free to choose whichever we are comfortable with. foam is really more efficient, that's why professionals use it. but since i am a diy person, i try to find cheap alternatives. a bunch of bottles will have space between them which will fill up with water, as opposed to foam which will be tightly packed. so effectively, the same compartment filled with foam will be more bouyant than if it had bottles inside. you can shape the foam to fit wherever you want to put it, but you can't do this with bottles. i do not need that much boyancy, so i can get away with this disadvantage. but just like most boaters, i appreciate extra storage space. but foam comes at a cost. because of this, i'm thinking of installing an alternative to my bottles. i intend to place thick plastic bags in smaler compartments, then blow the bag and seal the openings. the result will be an air bladder that conforms to whatever shape the compartment is. i am not yet comfortable with the idea because of the possibility of puncture, but i will do it once i see a suitable "bladder" material.

Yea your right, I didnt think about the density of water. Thanks!

I bought a sheet of polystyrene today. Its 2" thick and 4' x 8', it should be plenty to fill the front and back seat. This is what manufacturer did and its what Ill do.

Jdholmes · Oct 4, 2011

It is true that it isnt a matter of lifting the entire 1000+ lbs, but you still need around 12 cubic feet of foam and from what I am read that would be the equivalent of 17 five gallon buckets in buoyancy.

Tell you what, tape some small bottles in a couple of rows in front and back that take up no more space than your foam life jacket and strap it to your body...see if it keeps you as high in the water as the PFD. I have a feeling it won't...but I am not above being proved wrong.

The other strong advantage of course to the foam is going to be how you an spread it out so much more evenly. Ie along the bottom and sides of a boat taking up very little space.

Rat · Oct 7, 2011

It really is very easy to figure out:
1 cubic foot of water weighs 62 pounds
1 cubic foot of 2 part closed cell foam weighs 2 pounds
So, 1 cubic foot of foam gives 60 pounds of buoyancy
1000 pounds (full boat) / 60 pounds of buoyancy = 16 cubic feet of foam required
That is roughly a 4 gallon kit of two part foam; 960 pounds of buoyancy... Each 2 gallon kit is 8 cubic feet of cured foam.

The requirement for "upright and level floatation" mandated by the USCG is intended to keep the vessel, when completely swamped, right side up. Depending on the weight/ballast distribution of the hull this could mean as much as 30% of the buoyancy foam above the lateral center of gravity (COG). IOW you may need to add foam higher than just below the sole. The best places to take the foam above the lateral COG are at the four (or three) corners; port and starboard at the transom and either port and starboard at the bow or just a nice big area at bow (if you have a 'pointy' bow). Be careful when using foam that is not USCG approved. Not all foams are created equal; some will break down in contact with fuels/oil, some will absorb water faster etc... USCG approved foams have been tested for these conditions and are known to work.

Foam could save your life and may be required in some states and on some bodies of water regardless; but you should also consider the next owner. If you sell the vessel and loss of life, limb or property results from the modifications you have made it will open you up to liability; both criminal (less likely) and civil (more likely).

I'm not a lawyer, but I play one on the internet!

fool4fish1226 · Oct 7, 2011

I agree with Rat having foam makes for a safer boat and gives you a little piece of mind. If you fish alone not that big of a deal but when you have friends and family (Kids) along with you its nice to know that aleast you have a little added protection.

I used 2lb 2-part foam for my project. A five gallom kit costed me around $260 plus shipping and gave me 2400lbs of flotation. "Project A Little Snookered"

Do I need to add foam or other flotation?

Help Support TinBoats.net:

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Similar threads

Join the conversation!

Join today and get all the highlights of this community direct to your inbox. It's FREE!