Repairing floor in olf GRP / wood boat.

[guyd]

Hi - 2nd post /forums/images/graemlins/wink.gif

I have a small 17' fishing boat, open, unknown age / make / model. Looks a bit like an old style lifeboat, smooth displacement hull, may have been a day sailer originally.

previous owner appeared to be a ham fisted monkey - or at leat the last person to apply any fibreglass to it. The floor is separating from the ?stringers? in various places, and water (rain) has ingressed between the grp and the wood, separating it. It stinks. There is a bilge of sorts which used to house an inboard. The areas under the floor, but either side of the bilge are filled with expanding foam, which, (I was surprised) is dry.

I have cut out a new floor from marine ply (1/2") - some of the old floor comes up by hand, some is very very well stuck down. Old floor is ?3mm? ply with a layer of grp on top, some sticks, some doesnt.
Do I:-
a) persevere, and remove all the floor, and screw/glue the new floor to the supporting beams.
b) just screw the new floor on top, glueing where I can
c) other

The boat is pretty rough, and not worth much. Practicality is far more important than looks, and I would like this thing back in the water this summer.

 

[oldsaltoz]

Do I:-
a) persevere, and remove all the floor, and screw/glue the new floor to the supporting beams.
b) just screw the new floor on top, gluing where I can
c) other

G'day Guyd,

what option you go with will depend largely on what you find when / if you lift the old floor.
The ply separating may be due to rotted stringers or bearers.

The foam fill that looks dry may well be sodden if you dig a bit of it out, push a length of pipe into to take a core sample.

If the existing ply is showing any signs of rot it should be removed and replaced.

I suspect the glass is separating from the ply because the previous owner used standard poly resin instead of epoxy, so any glass not removed now separate later.

If you decide to replace part or all of the floor you can save a bit by not sheeting it with more glass, the ply have is thick enough.

However you should treat the new ply after it's been cut to shape and dry fitted to ensure it fits properley with a gap all the way round of 3 to 5 mm.

Use only epoxy resin, you can thin it 30% Methylated Spirits to help it penetrate, do the edges with great care, they will suck up a lot more resin because of the ecposed end grain. The ply MUST be very DRY before any resin is applied, and with low humidity, so dont do it if it looks like raining.

When installing the deck just mix some epoxy resin and micro-fibres (short bits of fibreglass) to make a paste like peanut butter, make a rounded gusset using a small jar or broom handle to give a consistent shape, then when tacky apply some epoxy resin cloth strips about 300 mg, the narrow strip first about 20 mm wider than the gusset leaving 10 mm each side of the gusset, next strip should be 30 mm wider and the 30 mm wider and the same for the last strip. for a smooth finish you can add a strip of rovings.

All that remains is a coat of epoxy primer then any paint you like.

The above can be used to replace smaller sections.

I hope this helps.

PS. At a pinch you could try drilling through the glass and injecting some epoxy resin and place some wieght on top till cured, the material from the drilling should indicate if the ply is dry, but with only 3 mm to play with you have to have a steady hand.

Good luck.

Avagoodweekend......

 

[guyd]

I have ripped a football size lump out of the foam to be sure - and its dry, its light, and theres no water at the bottom next to the hull skin.

I suppose I could drill out above the stringers and bearers, leaving 'spotfaces' of material using a flat wood bit. That would give me lots of spot points of contact for the glue....

The floor is hardly flat, and there is a repaired section where the sterntube is, which is so solid I cant budge it, this is the most 'mountainous' of it all. Ill make up a peanut butter splodges of epoxy and microfibres then, and use it like gripfil / no more nails etc?

Any suggestions as to a cheap place to order it from? Theres no chandlers here (Porlock, west somerset)

Thanks for the reply / help!

 

[oldsaltoz]

Check your local phone book for any fibreglass outlets or boat builder, much cheaper then chandlers.

If you drill the separated sections you only need resin, no micro fibres, you want the resin to flow under the glass.

Good luck.