smeaks
Well-Known Member
If stress cracks are very apparrent - how can they be repaired - assuming they were fender damage and the causing load has now gone.
reparing stress cracks in gel coat
- Thread starter smeaks
- Start date
damo
Well-Known Member
Stress cracks imply damage to the underlying structure, so best to get that checked out first.
For small areas you can grind out along the cracks with a tool like a Dremel then paint in some new gelcoat. If you are crafty it is supposedly possible to lay clingfilm over the gelcoat to produce a nice shiny finish, although I haven't succeeded myself.
For small areas you can grind out along the cracks with a tool like a Dremel then paint in some new gelcoat. If you are crafty it is supposedly possible to lay clingfilm over the gelcoat to produce a nice shiny finish, although I haven't succeeded myself.
Grajan
Well-Known Member
The Cling film is only to exclude air from the curing gelcoat not to give a superior finish.
elbow grease and decreasing grades of wet and dry ending up with 1000 grit then cutting compound and polish will give you a good finish.
Remember to clean off the area around the stress cracks prior to grinding out and filling otherwise grime will migrate to the crack and leave a dark line
elbow grease and decreasing grades of wet and dry ending up with 1000 grit then cutting compound and polish will give you a good finish.
Remember to clean off the area around the stress cracks prior to grinding out and filling otherwise grime will migrate to the crack and leave a dark line
VicS
Well-Known Member
Re: repairing stress cracks in gel coat
[ QUOTE ]
The Cling film is only to exclude air
[/ QUOTE ] You can also also use insulation tape. That goes on flat and if the crack has been filled to just the right level you can get a good finish which with luck might be acceptable with no rubbing down.
For me Cling film always ends up as a screwed up bit of plastic useless for anything!
[ QUOTE ]
The Cling film is only to exclude air
[/ QUOTE ] You can also also use insulation tape. That goes on flat and if the crack has been filled to just the right level you can get a good finish which with luck might be acceptable with no rubbing down.
For me Cling film always ends up as a screwed up bit of plastic useless for anything!
Grajan
Well-Known Member
Re: repairing stress cracks in gel coat
quote: You can also also use insulation tape.
Providing you are prepared to rub down the filled area
Acetone from the gelcoat filler can cause migration of the adhesive backing on the tape to penetrate the curing filler
and, gelcoat "shrinks" on curing!
quote: You can also also use insulation tape.
Providing you are prepared to rub down the filled area
Acetone from the gelcoat filler can cause migration of the adhesive backing on the tape to penetrate the curing filler
and, gelcoat "shrinks" on curing!
ChasB
Well-Known Member
Re: repairing stress cracks in gel coat
You can get heavy duty cling film from a catering suppliers (I've one down the road). It won't curl so much.
You can get heavy duty cling film from a catering suppliers (I've one down the road). It won't curl so much.
Superstrath
Well-Known Member
If you grind out the stress cracks and fill with gel-coat the crack will reappear in no time at all. The grinding needs to be deep, and a layer of glass tissue laid in before the gel-coat goes on top.
I have a fantastic book by Miles Wilkins - the authority on Lotus car bodywork - called "How to restore fibreglass bodywork." It covers all aspects of the subject in great detail, I haven't checked so don't know if it's still in print, I got mine at Beaulieu some years ago. I have taken moulds, made large parts, and repaired plenty of broken race-car panels following his guidance. Highly recommended before you take a grinder to your boat.
Alistair
I have a fantastic book by Miles Wilkins - the authority on Lotus car bodywork - called "How to restore fibreglass bodywork." It covers all aspects of the subject in great detail, I haven't checked so don't know if it's still in print, I got mine at Beaulieu some years ago. I have taken moulds, made large parts, and repaired plenty of broken race-car panels following his guidance. Highly recommended before you take a grinder to your boat.
Alistair
Krusty
Well-Known Member
Stress-cracks usually arise when pressure on the outside from a heavy breaking sea or another vessel thumping alongside bends the hull over a hard-spot on the inside.
There is no point in repairing stress cracks until the hard-spot is found and removed or relieved. It is usually part of the interior structure abutting the skin without sufficient glass fairing to spread the load.
The more lightly-built the hull, the more common the problem: and it often follows interior modifications (improvements?) by DIY-ers failing to take account of the flexibility of glassfibre hulls under external pressures.
I came across one boat whose owner insisted there was nothing whatever on the inside to account for a troublesome stress-crack. He was right, until I asked him to pull-out his chart-table; a sliding shelf over the quarter-berth which was hard against the hull in the extended position! The stress crack was precisely there on the outside.
There is no point in repairing stress cracks until the hard-spot is found and removed or relieved. It is usually part of the interior structure abutting the skin without sufficient glass fairing to spread the load.
The more lightly-built the hull, the more common the problem: and it often follows interior modifications (improvements?) by DIY-ers failing to take account of the flexibility of glassfibre hulls under external pressures.
I came across one boat whose owner insisted there was nothing whatever on the inside to account for a troublesome stress-crack. He was right, until I asked him to pull-out his chart-table; a sliding shelf over the quarter-berth which was hard against the hull in the extended position! The stress crack was precisely there on the outside.