Hull/deck joint

[bob26]

Can anyone throw light upon the filling of my grp hull-deck joint?

It is not the conventional biscuit tin arrangement. The deck sits of a shelf running round the inside of the gunwhale and the deck turns up to finish flush with the top edge of the hull - sort of like this: lUl where U is the deck and l and l the deck each side.

The joint is then glassed all round inside and capped with teak L-shaped teak moulding.

It has been leaking water into the main bulkhead and the capping needs replacing so I took it off. I was amazed to find the filler between the hull and deck is granular with quite large quartz-like particles. In fact what it resembles most of all is sand and cement!

The boat is 30 plus years old and may have predated todays ready-available epoxy fillers.

I've ground it all out with an angle grinder and I calculate its going to consume around 2 litres of epoxy to refill. Any ideas on what it was filled with and what else to replace it with??

<hr width=100% size=1>

 

[aod]

The granular quartz type of material that you have ground out sounds exactly like epoxy that has been flexing and therefore cracked and crystalized. My suspicion is that it will be almost impossible to stop this flexing of the said hull deck joint and thus impossible to prevent further cracking of any non flexible filler that you use. Another issue is that if you have found cracked filler in that specific area there is a distinct probability that other areas have also gone the same way.

I cannot physicaly see the problem thus my suggestion would be before doing anything either have a shipwright or a surveyor give it the once over.

You may well get away with using a flexible filler and packing but how you exactly deal with this depends on how long you intend to keep the boat.

<hr width=100% size=1>

 

[Hushinish]

I found a similar problem on my 24 footer, same joint as yours, when I removed the rubbing strake there was all sorts of mush in there. Some old books I have read recommend putty and scrim to fill the joint, I found that plus, polystyrene, wood filler etc.
Your chystals sound like resin to me.
What mechanical fixings are there? Nuts bolts and washers, self tappers, or pop rivits?

I removed all the nuts and bolts on my h/d joint, filled it with west system epoxy plus 403 micro fibres for bonding and strength. Then rebolted it with ss fixings. Seems a nicer joint now. I'm bonding and sealing the rubbing strake with sikkaflex which I'm hoping will keep water from hiding under the r/s and causing osmosis which it had previously started to do.



<hr width=100% size=1>

 

[charles_reed]

It depends on the builder, but the material sounds as though the filled the void with polyester resin which has subsequently fractured due to the constant movement.

Eposy would be slightly less likely to go the same way, but what you really need is probably a polysulphide which stands a lot of flexing but has considerable mechanical strength.
have a look at the Sikaflex range.

<hr width=100% size=1>

 

[aztec]

hi bob, had the same "stuff" joining the inner and outer shell on one of my dingies. ground it all off and used a two pack polyester to re-seal the gap. make sure you get the ratio right and it's not too warm... or it'll set before you get chance to work it.

i thought the thing had been laid up with brickies muck at first! but it was correctly identified as sand and polyester, and apparently was common for filling larger joints. hope this helps.

regards, steve.

<hr width=100% size=1>

 

[Guest]

Choices .....

After raking out and cleaining it best as poss. You can :

a) Acetone wipe to soften polyester faces and then fill with Polyester resin and glass strand mix ...... mixing enough to work 5 mins worth of joint at a time. So do it in stages ..... Make sure Acetoine has evaporated off before filling !
b) Mixing the Epoxy with a suitable filler such as Micro-balloons and then filling the joint.
c) Filling the joint with Sikaflex.

My choice based on :

Cheapest - go for polyester job
Strongest - Go for Epoxy
Most flexible, but expensive - Go for Sikaflex

??



<hr width=100% size=1>Nigel ...
Bilge Keelers get up further ! I only came - cos they said there was FREE Guinness !