Hi, my wife has a full carbon Allwave Vanguard Outrigger canoe.

It is only about 12 months old and we have just removed the cover after being stored for the winter to find an extensive 'roughness' on the gel coat - like tiny bubbles, really course to the touch. Also in places, there is visible bubbling, see picture.

She has only over used plain water to clean it (after ever use) and 'Car Plan bumper shine' to polish it, which was recommended by the seller.
It has been stored in a nylon sock and not come into contact with any chemicals. There was no problem when it was last used in October/early November - could frost have damaged it?

Firstly, can you suggest what might have caused the problem, and secondly what products do I need to repair it. I specifically want to know if I need to colour the gel coat (the boat has a multi-colour design!!) or will I be able to just sand away the bubbles and re-coat it with clear gel.


(The darker lines are reflection of trees)

Looks like there has been some osmosis happening and has caused the surface to blister.  I would sand back the bubbles and let it fully dry out indoors if possible. Then fill with a white gel coat and wax add. 

Hi Tom,

Thanks for your reply. That's good news that we can use standard gelcoat, however, I'm a bit concerned about how thick the gelcoat is as the carbon weave texture is visible, I would imagine to get a 7.5m boat including ama to weight 9.8kg, it will be thin. Also, how easy is it to match the colour?

I have also noticed, since posting, that the colour sections on the top deck seem to be applied vinyl sections as their edges are raised as opposed to being under the gelcoat, I am waiting for a response to the manufacturer as to what these are but if they are applied vinyl sections and the bubbling in this area is in the gelcoat under them, this will complicate things.

We are in Stoke-on-Trent, so within easy traveling distance of Nottingham. When you say you may be able to help, do you mean in assessing it further or do you do repairs?

It does look like potentially water damage, perhaps osmosis as suggested.  Ensure the boat is fully dried out before repairing.  A relatively simple gelcoat repair then sand and polish to match as described above will be whats needed.

If the damage is under stickers. you will probably need to peel them off and replace with new once the repair has been done.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

I've had this before, it looks like early osmosis but it maybe something else unknown.

Thanks for your replies,

ChrisR, unfortunately bringing it indoors is not an option being 7.5m (23ft) long, although I am trying to find a secure barn or such like to rent some space, so I may have to wait for the warmer weather for it to dry out properly.

Since my first post I've noticed that the bubbling is not around the open cockpit area but only around each of the bulkheads, which are sealed except for a small bung. Removing the bung revealed that both bulkheads are very wet inside (although no water seems to be flowing around in them), but there is crystalised salt inside - the previous owner used the boat on the sea. I'm leaving the bungs out but they are very small so will take a long time to dry out, would it be better to wash them out with fresh water first or just leave them to dry?

Interesting what you say about not storing it in a sock - it has been stored outside on tressles, upside down so water has not collected in it, but the nylon sock has been repeatedly wet and dried with the weather, so I this wont have helped. I will do as you suggest and remove the sock and if I can't get storage I will make something like an open ended poly-tunnel.

Warren, how easy is it to match the colour (white)?

Those don't look like osmosis blisters. Osmosis blisters tend to bubble to the point where they will pop open. And osmosis blisters won't just go away when left to dry out, once it's there it need to be opened up and washed and dried. What you have looks more like some kind of contamination in a painted surface. Either way the only fix is as suggested. Grind or sand them out and either refill the gel coat, or fill/fair and repaint.

Hi drcx, they are popping (see pic) and there is no sign that they are going away, in fact I dont see that they can, they are too big and even if they do the gelcoat where they were will be detached from the carbon.

I think that the fact there is salt water within the bulkheads is the cause as the bubbles are limited to area of the hull and deck above and below the bulkheads - there is no bubbling to the hull below the cockpit.

I cant see any alternative but to sand and refill but do I need to wash out the bulkheads or will allowing them to dry properly (with salt still in) be sufficient. I'm not sure of the best way to ensure the salt is removed other then run fresh water into them for quite a while.

Hi 

Hi Chris,
Unfortunately, it was bought second hand so the warranty does not extend to us.
And in any case I now think it is due to the salt water in the bulkhead - fault of the previous owner and our lack of knowledge in not checking and leaving it.
We would be interested in finding someone who can do this repair. I've done my share of car body repair but Im daunted by this because of how thin the gelcoat is.