Help with firefly!

[zany272]

Help!

A few days a go, I popped up to see the Firefly, and noticed the area around the back of the hull/ bottom of the transom, was looking very dark, and black. I gave it a poke, and water trickled out.
So, in it went back into the workshop. After some closer inspection, with the chisel, and some serious scab picking, a large hole appeared in the bottom of the hull where it meats the transom.
It seems all 3 layers have rotted through from the transom in about 2-3 inches.
The bit of, what i'll call beading, that sits on the inside of the hull where the hull meats transom, also appears to be pretty spongy in one place around the middle.
On the port side, the rot seems to go up under the gunwale, which means more fun to be had there.
Thankfully, the transom is unharmed.

So,
Questions (2 parts):

Part A

What to do with the boat.
I have some experience with hull repairs on the boat, but only on up to two layers, so there's always been something to glue to.
I have a sheet of 1.5mm ply from robbins , that matches well.
Do I need to construct a mold to form the first layer of ply around?
How much do i need to repair? Obviously the layer joints need to be staggered, but how far?

Part B

How did this happen, and how can i prevent it from happening again?
For the last few months, its been sat with the stern facing the weather, with the cover protecting the first 4 inches of hull from the top.
The varnish is the only reason I can think of. Its been on for around a year now, and has only been sailed once or twice due to our unique uk weather and our fantastic education system i am enslaved too.
When i took the scrapers and chisel to the varnish, it peeled off in slabs, leaving bear wood, and i can only guess that the varnish was letting the water in, but then not out, resulting in the rot.
So, what to do.
The varnish was 'hemple favorite', that i picked up from a boot jumble. It seemed really good when it was first put on. I put on a few thinned coats to soak in and then built up the gloss on top of that. All seemed good.
Is this varnish known for this? I would expect more than a season of sitting in a garden out of a varnish!
I have been looking at some alternatives.
Djeks oil, looks good, because it soaks in, and then a big gloss in built up, but it does look expensive, and i haven't come across it on a hull before.
Epifanes looks pretty good, although expensive also.
Or, my least favored, 2 pack polyurethane. I have to say im sacred of this stuff, because if i muck it up, it will never come off again, ensuring maximum pain for both me and the boat.

With exams and tall ships in the summer, this sadly isnt a priority, but does mean i have a lot of time to think about it....

Here are some pictures that might be able to make sense of that rabble..

https://plus.google.com/photos/10943448 ... pzE677UngE

Thank you very much,

Will Paterson.
F272.

[chris]

I except Ed or Rupert can give more help than I, and it may be worth doing a forum search. as much has been written about repairing these types of hulls on this forum.
But here are my thoughts .
Remove all rotten wood.
But leave the layers stepped. One of your photos shows the three layers with smaller and smaller holes. That's helpful because if you do the middle layer first you then have something to work on for the inner and outer layer. So you are able to glue the middle layer to what is left of the layer with the smallest hole. My choice would be to use thick veneer rather than 1.5 ply, (see what others suggest).
I don't think you will need to make a mould, unless it is a huge hole but you might have to be a bit creative when it comes to holding the layers you are gluing in place.
I'm not sure why you have had such bad luck with the varnish. It sounds as if you did everything right. Maybe the varnish was very old, maybe the wood was greasy, but most likely I guess was that the water found its way in through a joint then went along the inner layer of the laminate gradually rotting it from the inside out and then just lifted the varnish. If the boat was cold moulded and used something like Aerolite this may have started to fail and will make a nice passage for water. I've also found on my old merlin that the inner layer of the ply is not mahogany and is rotting whilst the outer layer may look OK.
good luck.
chris

[Rupert]

Hi Will,

I think Chris has hit all the main points. This is very common in Fireflies, sadly, where the final bit of water can't get out through the bung holes and so sits there for years on end. If you cut the layers as Chris suggests, you won't need a mould. Thick veneer is the way to go on the mend. The outer layers need to be fairly accurate in the fitting, but the middle layer can actually be better if there are small gaps round it, as that way the epoxy will join right through top to bottom.

There is much more on the forum about all this (and some on the main site, I think, but not sure). Worth a good look round.

[zany272]

brilliant,
cheers Rupert and Chris.
An ideas as to what varnish to put back on?

[Rupert]

There are as many views on that as there are people on the forum...

I guess we would all agree that getting the hull sound before varnishing is the secret. What you then put on is a matter of choice. I like traditional varnish - easy to use, looks nice, easy to sand and put another coat on, but not as tough as a 2 pack.

[JimC]

There are as many views on that as there are people on the forum...

I'd say more views than people on the forum, since many if not most of us will offer up two or three alternatives depending on what's being varnished!

[GAVinT]

Hi Will, I have a complete Firefly(named Butterfly made by Fairy Marine,circa 1962)sitting in the front garden.
I sailed her twice last year but after moving and dropping out of a Reservoir Club, in favour of going back to a small river cruiser and rejoining a club on the Stour, am wondering if I will realistically be using the dinghy. I did consider it as a tender.
The boat had two obvious large hull repairs which showed no sign of water ingression, from that source,however once I put some decent bungs in she went very nicelyand I went mad and painted the hull black when upside down before the winter.
The only trouble I had was getting the sail and subsequently boom high enough to be comfortable .Since I fitted a cord hallyards, so the sail goes up fine.

If you are at all interested £75 sans trailer or trolley.
Situated near Harwich Essex.

[Ed]

Looks well covered by Rupert and Chris,

it would be worth searching in the forum as it has been discussed at great length before.

however I don't think there is anything on the main site. We have talked about writing it many times as the subject keeps coming up, but don't think we ever got around to it.

Veneer is certainly the way to go and hot ply. When I last looked Robbins in Bristol had plenty of Agba veneer in stock.

It is a very easy and fun job to do.

If you are up to it, you might want to review the recent thread about using vacuum to pull down veneers. This could work well for the exterior veneers on inside and outside.

cheers

eib