Really cheap GRP repair

[JerryRhum]

I recently bought an optimist for £40.

The seller was very honest about the state of it, but I only wanted it for the mast and sales.

I took the boat away as well and have been letting my kids play 'pirates' with it in the back garden.

However......... I can't help wondering if I could patch it up enough to let the kids actually sail in it every now and again.

Is there a cheap and easy way to deal with the damage in the pictures? I'm thinking a bit of filler, sealant and a coat of paint, but I've never done anything like this before.





cheers
Jerry

 

[Gsailor]

I would grind out the cracks to make them a bit bigger to accept epoxy or polyester resin mixed with a filler (epoxy is more expensive but adheres better than polyester resin and epoxy is better for repairs imho) and then I would use fibre glass tape over the holes on the edges etc and then I would sleeve (or is it sheave?) the hull in thin (like tissue paper) glass fibre and resin. There are different grades of fibre glass - chopped Matt, woven ( heavy duty) etc - the thin tissue paper like fibre glass is the lightest duty. Then clean up, prime and paint.

There may be YouTube videos.

How cheap is cheap to you? It would not cost a lot in materials (well I have not checked recent prices of epoxy - many commodities have increased in price). Polyester resin would be cheaper.

 

[Stemar]

I'd just grind off the loose stuff and epoxy a bit of glass cloth over it. Maybe 2 or 3 layers on the damaged edges

 

[fisherman]

I'd just grind off the loose stuff and epoxy a bit of glass cloth over it. Maybe 2 or 3 layers on the damaged edges

Get some 600gm chopped strand mat, polyester layup resin, acetone, paddle rollers, brushes. Fom CFS cornwall if no one nearer.
Grind until cracks disappear, taper the edges, if the hole is big enough put a plastic bag of sand, or gaffer tape inside, patch outside, then patch inside to connect both sides with fresh layup. 3 x 200g csm and Polyester resin, dab the resin into the mat and roll out the bubbles until the mat is all wetted, do three layers at once, any more and it gets too hot. It will bridge small holes. It's best to wetout and roll the resin/mat on a sheet of scrap ply or plastic, then lift with brush and roller onto the repair, push and roll into place. Then clean brushes, rollers, hands, arms, face, hair, workbench, car, wife, kids, patio and anything else within five feet of where you did the job.
Don't waste time on cosmetics.

 

[B27]

As above.
But disposable gloves save on the cleaning up!

 

[fisherman]

As above.
But disposable gloves save on the cleaning up!

When I and a friend built a 25ft FV he used to don his 'layup trousers', a pair old denims which were absolutely rigid and a good half inch thick.
Disposable hazmat suit is favourite now.

 

[VicS]

It would be a shame not to patch up an other wise decent Oppie.

Some good advice above. Consider using epoxy resin because it will adhere better than polyester. More expensive though and cannot use the same chopped strand mat as polyester but woven cloth or tape is perhaps easier to work with.
Don't try to bodge it with body filler

There is loads and loads of advice on the West System website. Although West resins are epoxy the techniques are equally valid if using polyester.

 

[fisherman]

CFS sell all the West System gear as well. I haven't ever used epoxy this way so no knowledge of it.

 

[Supertramp]

Glass mat on the inside to strengthen and seal, fill on the outside. Paint the new mat to ensure no spiky glass for bare feet. Power sand the outside if you want a good finish. Did an old canoe this way and it's lasted well.

 

[Boathook]

Is the damage visible inside the boat. If so some 'tape' with epoxy over the damage. I would use epoxy with microfibres mixed in to fill the holes once clean, sand and some paint to smarten up.
Epoxy sticks better to polyester than polyester resin and is about twice the strength. I would avoid car filler / plastic padding as it seems to go soft when it has a lot of water on it for a period.

 

[fisherman]

I would avoid car filler / plastic padding as it seems to go soft when it has a lot of water on it for a period.

I was told it is designed to absorb water for wet and dry sanding/

 

[JerryRhum]

Thanks for all the replies.

I'll have a search on the CFS website and put a shopping list together. From first glance it looks like I'm going to spend more on repairing it than I paid for the dinghy, but I guess that's why it was so cheap.

I've checked the inside and there are no holes or cracks on the interior hull, so that is good news.

This is the inside view of where the worst damage is on the outside:





I'll have crack at repairing it as the other option is to use it as a sandpit!

cheers
Jerry

 

[dunedin]

Of course the really cheap (and temporary) “solution” is to cover with gaffer tape and take it sailing!

Many decades ago got a hole in the bows of a Mirror by hitting the ruder of the boat in front st a mark melee. To finish the event was gaffer tape to cover the hole. Seemed to leak less than previously.
Didn’t have time to fix before next event. Gaffer tape still fine.
Painted over the black gaffer tape and left till end of season to repair properly over the winter
Not recommending this technique, but old Oppies are tough beasts.

 

[William_H]

When I and a friend built a 25ft FV he used to don his 'layup trousers', a pair old denims which were absolutely rigid and a good half inch thick.
Disposable hazmat suit is favourite now.

Brings to mind where I saw an old gut a long time back whop was getting old denim jeans. He cut them to shorts and fitted wood to seal off the leg holes. He then soaked the whole lot in polyester resin to make a plant pot.
To the OP I would not consider sheathing the hull. Just fill the dings with filler. Epoxy with filler or car body filler. Sand back and paint. Yes OP might spend money on materials but get a whole lot of learning of new skills. ol'will

 

[Gadget257]

My wife for my birthday booked me a practical fibreglass days course at West Country Boat Repairs | boat repairs in west country, wales, and west England (i think the price was £95 a head). I cannot recommend the course enough to you as it will give you the confidence to work with fibreglass (hole filling, grinding and sanding) and I have no doubt the boat will be looking probably as not as new but very close.

 

[Supertramp]

A minor repair where the hull is worn through on the edge is easy and necessary as flexing when you step in and out will crack a filler only repair. After any holes are made good with resin and mat (with sand and clean before applying resin) it's up to you how much work to do filling cosmetic holes.

Worth doing even just for experience.

 

[ylop]

Don't try to bodge it with body filler

Its a 40 quid boat and he wants a cheap quick fix so I wouldn't rule out the bodge it approach yet!

I would avoid car filler / plastic padding as it seems to go soft when it has a lot of water on it for a period.

In the 90s we used to bodge repairs together with plastic padding all the time. It would usually last the season if it was done well, then we would grind it back out at the end of the season and do it properly indoors over the winter. The failure point was always the quality of the prep on the old bit the filler was stuck to rather than the filler itself - that was the same for boats kept on the water and those kept ashore. Any below the water line repairs on anything being kept afloat were painted on top of the filler (actually the boats going on/off trailers took far more of a beating than those kept afloat). I don't recall any being soft when we ground back out at end of the season - and although some rushed repairs would fail before the end of the season it was almost always the whole lump of filler fell out (ie the issue was the filler to GRP joint) rather than the filler itself failing. I'd happily do it as a cheap fix on a cheap oppie ** anywhere that met these three criteria:
1. was not through all the way through the hull (i.e. if it fails its not leaking)
2. was not on a panel/joint that was able to flex with the force of your thumbs close to the repair area
3. that was dry and solid to attach to.

If you do it: prep is key - get fresh material (we used a surform, rasp, file, with modern battery power tools likely even easier). Remove dust & clean with solvent. Get it thoroughly dry. Make sure it has a decent time to set before putting in the water or painting over. If you are going to sand it, make sure you give it at least 24 hours first. We would usually fill it and leave it 3 days before doing anything with it. We kept a fleet of about 10 dinghies going for 6 years with this approach (and it had been the same for many years before me - I moved away after that but they probably still do the same).

** I am assuming this oppie will be used in circumstances where a sudden failure is no more life-threatening than the very likely prospect of a capsize and the kids have some easy way to be recovered.

Worth doing even just for experience.

He has a choice - £20 on filler, £20 on sandpaper, grinder disk etc, and £20 on paint a few hours work and a £100 boat that will last a couple of seasons and might need to be done again (but which point the kids may have lost interest / outgrown it).

OR do it properly, probably spending £200+ on materials and a couple of days work and he'll have a boat that might sell for £150 (unless he puts in a lot of effort (and more £) its still going to be a patched up old boat).

 

[fisherman]

OR do it properly, probably spending £200+ on materials and a couple of days work and he'll have a boat that might sell for £150 (unless he puts in a lot of effort (and more £) its still going to be a patched up old boat).

A kg of resin is a tenner. 450gm mat is £2.50/sq m. then it's just brushes and rollers and acetone. £25-£30?
For comparison I did a Nidaplast deck in a IP12. Five layers of 600gm on one 8x4 sheet was about £80. So 160sq ft of 600gm layup was about £80, or 50p/sqft.

 

[ylop]

Are those recent prices?
- 1.2 kg of west system was £50 in the Swindlery last time I looked
- then at least some people are suggesting tissue as well as mat, probably want microballoons or fibres too? Probably £50 worth unless you can buy in small quantities, more if covering all in tissue?
- then I assume if going to all that effort you finish it nicely with gel/flow coat - if you go epoxy (for simplicity) elsewhere you need expensive flow coat too! £50
- add your consumables, grinding wheels etc and I think you’d be doing well at chandlery prices to spend less than £200. Can probably do it cheaper buying online - you could certainly do it for less with polyester, but last time I bought everything I needed for a repair it struck me as really expensive for a simple job - now I have a load of stuff left over, but starting from scratch it all adds up.

 

[fisherman]

Are those recent prices?

Today's prices:
CFS Catalogue

but only 'really cheap repair' as the OP wants, polyester, csm, as per my rundown in #4.