Small hull repair

[Misterbreeze]

I'm replacing all the skin fittings on a grp hull and need to make flush where one of the old ones was recessed, 2-3mm deep. There are also 8 bolt holes to fill where the old Blakes fittings were removed. Can I get away with an auto body type filler (which I've already got) as it's such a small area or do I have to fork out 30 quid for a little tin of "marine" filler?

 

[AntarcticPilot]

Basically, auto repair stuff is slightly porous; it's meant to be finished with an impervious paint coat. Marine stuff is impervious.

I think the resin is the same or similar, but the filler is different.

It's also better to use an epoxy based filler - it will adhere better to old GRP.

 

[Fimacca]

I would Buy the proper stuff !

 

[Refueler]

Being a cheap skate ... if its a recess and not through the hull - I would use your auto filler ... first of all getting surface really well prepared to get best adhesion.
If through hull as well - then a patch covering the area and out for a few cms inside glassed in would be prudent to create a strong repair.

Once filled and sanded - a nice coat of epoxy primer to seal and then Antifoul .....

The bolt holes ... I would fill also - but as an added precaution - I would glass a thin matt inside covering all bolt holes and surround ....

 

[Neeves]

Just a few thoughts

Is the vessel worth investing stg30 for the correct material, see post 3. If it sinks on its moorings will you notice the loss, see post 2

If there is a loss, if you have insurance, will your insurance still be valid.

Jonathan

 

[PCUK]

All good points!

 

[Graham376]

Quite a few years ago I used car body filler to fill some casting holes in our cast iron keel then Jotun Vinyguard and antifoul over. Still there, well attached.

 

[AntarcticPilot]

Quite a few years ago I used car body filler to fill some casting holes in our cast iron keel then Jotun Vinyguard and antifoul over. Still there, well attached.

If finished with an impervious paint layer such as your Vinyguard, car body filler would be fine for a non-structural repair as long as the paint remained in good condition. If used to fill holes, as the OP wants to do, both sides of the repair would need to be sealed with suitable paint.

 

[Refueler]

If finished with an impervious paint layer such as your Vinyguard, car body filler would be fine for a non-structural repair as long as the paint remained in good condition. If used to fill holes, as the OP wants to do, both sides of the repair would need to be sealed with suitable paint.

Why not just as I suggested - apply a GRP matt patch inside ?

 

[AntarcticPilot]

Why not just as I suggested - apply a GRP matt patch inside ?

Sure, but if the OP had glass and resin available, why would he be asking about filler? Better to do it properly by bevelling the holes and laying up glass and resin, if glass and resin are available.

 

[Refueler]

Sure, but if the OP had glass and resin available, why would he be asking about filler? Better to do it properly by bevelling the holes and laying up glass and resin, if glass and resin are available.

Agreed ... but I have also filled and then glassed over ... both ways work. When its bolt holes etc as he talks about - filler + matt is easiest IMHO.

 

[lustyd]

What are the new skin fittings? If they are TruDesign or similar they need a decent structure to attach to to avoid flex, so check that the hull is thick enough to prevent that and I'd even consider glass mat and resin for the repair to put structure back rather than a thickened epoxy filler.

Why not get a recessed replacement?

 

[Misterbreeze]

Thanks for the responses...the replacements are Trudesign but rashly I removed the old and bought the new ones without realising that one of them was recessed in this way. Fortunately it's one of the smaller ones, 3/4 inch, and the layup is thick enough to mean that flex isn't a concern. It's really only the gelcoat that's been removed. All things considered, I'll make good with a proper marine epoxy otherwise it'll always be a niggling doubt.

 

[Mister E]

You can purchase auto Fibre Glass Repair Paste. It is chopped strand in polyester resin if I remember correctly.

 

[PaulRainbow]

You can purchase auto Fibre Glass Repair Paste. It is chopped strand in polyester resin if I remember correctly.

P40

 

[Laysula]

30 years ago my mates boat sank when he used plastic padding marine filler. Upon reading the info sheet afterwards it did say "Not suitable for below the waterline"
Be very carefull what you use and read the data sheet.

 

[Refueler]

You can purchase auto Fibre Glass Repair Paste. It is chopped strand in polyester resin if I remember correctly.

The better is Devcon ... which is suitable for all uses ....

Can be bought in pre mixed with chopped strand - or pure paste only ...

It has various grades as well ...

It does NOT have a Marine based price !!

 

[Refueler]

30 years ago my mates boat sank when he used plastic padding marine filler. Upon reading the info sheet afterwards it did say "Not suitable for below the waterline"
Be very carefull what you use and read the data sheet.

That's why I always advise adding a layer of matt and resin inside as 'security'. Regardless of what filler you use ... because with movement of hull ... temperature variations you are not only relying on the fillers adhesion in the hole ....

You only have to see a 'filled' hole later on and see the 'creep' of the filler ....