Boat Mods

[Doby]

Guys;

I have modded about 10 FE boats to date and built over 25 ( gas / scale) in total over 20 years or so...one thing that still amazes me is that more people don't use expandable foam as structual material for re-inforcing hulls. Its the best thing going,,,I just used it again in my Super Hawaii mod and it makes the hull strong as a rock with almost no increase in weight and adds flotation:D .

Its a win / win situation all around. Just be sure to use the LOW expansion stuff and add it in stages otherwise the hulls can be pushed out of shape.

Also , once its dry and has reached full expansion , you can cut it, file it to whatever shape you may need to install batteries etc.

Just some advice on what has helped me out over the years.:)

[JimClark]

doesn't it suck up and hold water?

[Darin Jordan]

doesn't it suck up and hold water?

It depends on what type it is... True Two-Part expanding foam works pretty well... just don't get it into a confined space... or POP goes the seam...

[Doby]

It doesn't suck up water at all , it just makes thing incredibly strong and bouyant

[SJFE]

Name and Brand please Sir:)

[yz120]

great stuff low expansion foam works great.
available at walmart.

[Doby]

SJFE ; you are alive :) :)
I just saw ABC news and was wishing you the best. What a disaster
I use great Stuff as well , most brands are OK , BUT MAKE SURE ITS LOW EXPANSION. I'll attach some photos of my applications soon .

[Doby]

Here are some shots;:D
http://i167.photobucket.com/albums/u...amFills001.jpg

http://i167.photobucket.com/albums/u...amFills002.jpg

http://i167.photobucket.com/albums/u...amFills003.jpg

[Steven Vaccaro]

The reason I never used it was that everyone says that it will expand when exposed to the heat from sitting out in the sun. If this is incorrect it would really be nice to use for abs hulls.

[SJFE]

Thanks Buddy:D. I am of to put the last few touches on the Bullet. I look to run very soon:).

[Doby]

Steve/ SJFE, 20 years of hot temps / sun and never any extra expansion !

[JimClark]

what about sanding it to shape it ?
Jim

[Doby]

I've done it using a very coarse grit , it works well , even a Dremel works as well !

[Drunken Pirate]

Doby,

Great Tip, thanks. It's nice that you have already done the years of data collection on this.

DP

[Jeepers]

I have also used the expanding foam in my classic hydros kit made the hull solid and so far its had no problems in the sun and its been in 100 degree weather. and with the crazy temps in colorado somthing would have shown by now!

[boater76]

Cool. Sounds like a great idea. I was thinking about using the stuff but wasn't sure. I am going to use the stuff on my SH knock off.

Ken

[boater76]

I used the Great Stuff on my Super Hawaii copy today and boy did that stuff stiffen the hull up. It worked great. It did add weight to it, but hopefully it won't take away speed from the setup I have planned.

Ken

[Steven Vaccaro]

Is this the stuff you guys are using?

[Doug Smock]

doesn't it suck up and hold water?

It sure can!! After it has cured it has a shiney outer surface. If it is disturbed it can ( will ) soak up water like a sponge.

Doug

[Steven Vaccaro]

It sure can!! After it has cured it has a shiney outer surface. If it is disturbed it can ( will ) soak up water like a sponge.

Doug

What do you suggest Doug?

[Doug Smock]

I would seal any disturbed area with a sealer of some type.
I personally use styrofoam. I'll cut it to shape so it fits nice and snug, seal the cut edges with Polycrylic ( by Minwax ) and glue it in the hull with a mixture of Gorilla glue and water. The glue expands as it cures and fills any gaps. And it is lite.:)

This is the floatation ( and deck support ) before I installed it in my Titan 29.
It fills the hull from the keel to the deck, and two strips down the side.

I understand that Doby has had good luck with the expanding foam, but I have seen a couple of boats nearly destroyed by Great Stuff and the two part urethane foam. Could have been the user, I don't know.

Doug
PS I did my P-Mono SAWs boat the same way. I blew that boat off more times than I can count at 60+ mph chasing the record for two days. The hull doesn't have the first gellcoat crack in it.

[ED66677]

Hi guys,
You can use extruded foam but not expansed foam, in France such material are both used for house insulation, I've built RC plane for 20+ years and expansed foam is commonly used for building wings (funboard as well), but once shaped, it is requires to wait few days because it continues to expands a little, extruded foam doesn't, it's heavier, stronger and more difficult to work (mainly used for small gliders with thin wings), the first boat I built was entirely made of extruded foam (without any covering material) I can tell you it doesn't suck water at all, hot wire cuting makes a thin layer of melted foam witch is somehow waterproofing the material itself, like a skin, but even a paper sanded surface doesn't suck water, it only retain a bit due to very small cavities on the surface, and the next boat (http://perso.orange.fr/pleindetrucs/madrigger.pdf) will be also made of extruded foam and I will used thin pre-made carbon sheet to cover it, it's gonna look nice, it is weight saving only if used with fiberglass or carbone, wood covering is generaly heavier than a classic "empty" structure!
For assembly I use Polyurethane glue (sometimes combined with charged epoxy glue), this glue expand a little bit but stick on any material except PolyEthylene or PolyPropylene, and because it's Polyurethane once dry (or cured) it doesn't move at all, Polyurethane glues are the top gluing material used in automotive, water resistant, heat resistant and solvant resistant!

[boater76]

I noticed that on the bottom of the hull that there is a little bow coming out in the one spot. I apparently used to much. Hopefully it doesn't screw the thing up that much when it comes time to put it to water. Oh well ya gotta learn somehow.

Ken