Filling boyancy tubes with expanding foam.

[tonybarebones]

I have a small RIB which I keep on davits, the boyancy tubes are shot so I came up with the idea of filling them with expanding foam, does anyone have any experience in doing this type thing? /forums/images/graemlins/confused.gif

 

[vyv_cox]

In general, expanding foams that the DIY enthusiast can buy are not closed cell types and they will absorb water. I used to build canoes with youth organisations where it was common practice to fill the ends with two-pack foam bought from Glasplies. After a couple of seasons during which the canoes were capsized on many occasions, we realised that they were considerably heavier than when built. It was quite a job digging the stuff out; it was saturated with water.

If you have access to professional closed-cell foam it's a different matter, but these pose considerable health risks due to MDI or TDI and are not usually available to amateurs.

 

[Bajansailor]

We did this for a customer once, to an old tired Avon Redcrest ,when I was working in a yard that built fishing boats and insulated ice boxes - filled up the tubes very nicely, but it was a fair bit heavier, and I think that the owner reported later on that it was not a success, cos it did seem to absorb water - if you can use guaranteed closed cell foam as Vyv notes above, it could be feasible.
Always a possibility though of big voids in the tubes, which would be difficult to fill without making new filling holes locally.

 

[Fascadale]

Hi

I bought a 17ft open work boat with an internal molding creating forward, side, stern thwarts and floor. The voids were filled with blocks of polystyrene foam wrapped in polythene.

The whole lot was sodden. I removed it all.

Good luck

 

[barryhall]

You can buy closed cell foam from http://www.spray-insulation.co.uk/index.htm
However:
a) it is not cheap £250 ish for kit
b) you would need to cut more holes to fill it completely
c) as Vyv says it is hazardous and needs to be done in good
ventilation ie outside

Barry

 

[William_H]

I can't help thinking you should either repair the air filled tubes so they hold air or buy a new dinghy. olewill

 

[eidiohir]

Pal of mine filled under the deck of a 14 foot dory with old plastic mineral bottles to cut down on the volume,then filled it with closed cell foam which he "borrowed" from work.Two years now and counting and seems to be OK so far.

 

[boatmike]

I think the cost of doing it properly with 2 pack syntactic foam, which can be bought from and GRP supplier incidentally, would be prohibitive and add more weight than you think. If the outside casing flexes it would also crack up as it has very little mechanical strength.

 

[Lakesailor]

I'm with ole will. All that time and effort (and cost) for a shabby old rib that is heavier than it should be.
Get a new one.

 

[tonybarebones]

Hello everyone, thanks very much to you all for the info, it seemed like a idea at the time to fill the tubes with expanding foam but now, thanks to you guys I'll save myself a lot of time and heartache. /forums/images/graemlins/grin.gif

 

[explores]

I have a unsinkable ? swift explorer, how can i check what kind of foam has been put in it? It,s near the gunnels and can be got at easily. It was put in by the manufacturer.

 

[Topcat47]

Ribs can be re-tubed. The more work you can do yourself, the less it will cost. If the basic hull is sound, it could be a cost effective solution.

 

[Topcat47]

If the foam is readily accesible, you could remove a core and ask Scott-Bader or Wests, asking them to identify it for you. You'll need to pug the core though. I'm assuming the manufactured of the dingy is defunct.

 

[Cruiser2B]

That's too bad - I thought it was a clever idea. I don't imagine foam would add too much weight, so if the only worry is from water being absorbed, then why not seal the inside of the tube first with a urethane sealant?

 

[Graham_Wright]

I wonder if there is a safety opportunity here?

Middle of the oggin, miles from rescue, container holes hull, sinking. Liferaft and possible rescue.

It is always advised to stay with the boat whilst it is afloat.

Pop down below, see rapid inflow, discharge the instant expanding foam and maybe seal or slow the leak and maybe add sufficient bouyancy to stay afloat and maybe even save the boat.

Don't think we would worry too much about absorbtion in those circumstances.

Daft idea?

 

[rogerthebodger]

There was an article in PBO a little time ago about inflatable bags inside a boat that would keep the boat afloat if totally full of water.

Have considered it for my new yacht but would need at least 18 cubic meters to keep it afloat.