Blue Foam (Where?)

[Don Templeton]

Some one on this forum said where to get blue foam for sponsons

but I can't find it now! Might have been Mike P But I'm not sure.

Could use some help!

Don :

 

[MikeP]

I got spyder foam from aerospace composites. It's not kledgecell, but it's some good stuff. Stay away from the insulation type foam from the lumber store.

-MikeP

 

[TomMoorehouse]

mike...... why no insulation type foams? i use the pink foam and never had a problem....

don the pink and blue foam are the same stuff.

 

[MikeP]

Tom,

I guess that statement wasn't said well. I have used the insulation type before. on my .12 rigger and JD wolf and didn't have any problems. I got the spyder foam and like working with it much better. It's alot harder cuts and sands nice. I got a 2'x4' sheet 3" thick for about $20. I could only find 1.5" thick insulation and had to glue two pieces together.

-MikeP

 

[Don Templeton]

Thanks guys,

Just before your reply I finally found where I wrote down the

web site that you mentioned MIke. However,while searching the

web I did find a lot of information about foam and in several

places it says that the pink foam does not have the density that

the blue does. I think either one will work fine for me but I do like

the size and availability of the spyder foam ( used to be white for

surf boards but is now blue.)

Thanks again,

Don

 

[Hammerhead]

Make sure that it has a urethane base, or epoxy will melt it. I'm sure you have it down though. Ask Tom about carpet tape! It is great stuff when making sandwich type sponsons. I can't live without it now.

Hammer

 

[jeff baham]

mike p., what type of glue are you using on the spyder form. can i use C-A ON IT.

 

[MikeP]

Jeff,

I tried CA on spyder foam and it doesn't work, the ca eats the foam. I use epoxy.

-MikeP

 

[Don Templeton]

MIke:

Does the Spyder foam cut easy with a hot wire and can you

cut it well on a table saw to get a good clean square edge

for the initial block cut.

 

[Don Templeton]

Tom:

Do you use carpet tape to hold on the templet? Does that work better

than double sided scotch tape?

 

[TomMoorehouse]

i dont actually use carpet tape....it a tape that we use at work that is very simmilar to carpet tape. I use it for a bunch of stuff!

 

[MikeP]

Don,

I haven't used a hot wire on anything. I don't see why it wouldn't. They make airplane wing cores out it of all the time using a hot wire. I use a hack saw blade to cut mine, I will give the table saw a try, that should make some nice clean cuts.

-MikeP

 

[Don Templeton]

Well, I think thats enough information to get me in plenty of trouble!

Thanks

Don

 

[Hammerhead]

I match the square edge of my outer and inner sponson walls with a known square edge of the foam. I then sandwich the foam with the pre-cut walls using a carpet tape( took me a few tries to find good stuff). My walls are white birch with a layer of 18 inch balsa. I put the carpet tape on the balsa first, then line one side up with the foam, and stick it on. I use a square and line up the other side, and stick it on, too. I then cut the excess foam off with a box cutter with the blade extended all the way out. I get it as close to the wood as I can, then I carefully block sand it till it is perfect. I then dig trenches where the cross beams will go and epoxy them in. I put the planking on with epoxy. The layer of balsa and plywood plus the cross beams provide a good ledge for bonding the planking on.

My style of sponsons (coined by MikeP as the hammercut), are perfect for this method.

Hammer

 

[Don Templeton]

This is not the "Hammercut" design but a more conventional design.

Your design looks pretty easy to build except how do you do that

last cut out along the outside bottom.

I have attached a couple of drawings of a conventional design and

tried to show how I would go about building it. This will be my first

attempt at building sponsons so let me know if it makes sense.

 

[Don Templeton]

2nd picture with how I plan do go about it. (Hope you can read it.)

Click on lower right to blow it up a bit-I think!

 

[Hammerhead]

I believe this is the sponson design that MikeP used on his 3.5CF rigger.

This is the same style of sponson that I used on the Hammerhead 90.

It was also used on the anzai maru, which won the JMPBA Nats 2002.

It has a hammer cut.

Hammer

 

[Don Templeton]

Thanks Hammer,

It took me a while to figure out the drawing but after spending some time

on this forum checking out Mikes 20 thread, his new thread and your 12 thread

it finally made sence to me. The hammer cut is growing on me!

If I remember correctly, the old Crapshooter sponsons had a block of wood with

the inner tubes glued and screwd into them. Kinda heavy for todays standards.

Thanks again,

Don

 

[Hammerhead]

Hey Don! I went back and looked at a lot of pics that Mike sent me of

His 3.5 CF. It does look like he made them almost exactly like this.

The .84CF sponsons have a similar cut, but they seem to be quite a bit

shallower.

Hammer

 

[Hammerhead]

In this drawing the outer tubes for the sponsons only goes half way. This is a design originally

intended for a .45 or bigger. With a smaller boat, I would highly recommend

making the sponsons outer tubes go all the way through, and don't use a center reinforcement

wall.