Fairey Hull Repairs

Background

Fairey Marine built the Flying Dutchman, Jollyboat, Falcon, 505, Albacore, Swordfish, Finn, International 14, Gannet and Firefly classes of racing dinghy by the “hot moulding” process.

These were the finest mass produced dinghies ever made; the construction technique resulted in a light, strong, durable and very pretty hull which is infinitely repairable, whilst the fittings are beautifully made and equally durable.

They also built the Duckling and Dinky tenders and the Huntress, Faun, Fisherman and Cinderella powerboats along with the Titaniaand Atalanta sailing cruisers and the 16ft Fulmar dayboat by the same method. Between 1946 and 1963 Faireys had built over 7,000 hulls this way; of these, more than 3000 were Fireflies and another 1,000 or so were Albacores. The other dinghy classes are much less numerous; some are very rare.

Because the Firefly is the commonest Fairey built boat, this is written with particular reference to the Firefly as it is the Fairey boat that most people will own first; owning Fairey boats is addictive but since the construction is very, very similar, once you have repaired a Firefly you can repair any other type.

The hot moulding process was an adaptation to post war boat building of the method originally developed by de Havillands in the 1930′s for “stressed skin” wooden aircraft production, using layers of thin birch plywood sandwiched together with glue over a male mould and “cooked” in a large oven called an “autoclave”. The DH 88 Comet air racer, the DH 91 Albatross passenger transport and the DH 98 Mosquito were all built using this method, initially using casein glue. During the later stages of the Second World War some de Havilland “Mosquito” bombers, posted to hot and humid airfields in South-East Asia, broke up in flight, due to glue failures in the hot moist conditions, and a more durable glue, “Aerolite” urea formadehyde, with formic acid as the hardener, was substituted. Faireys considered that this technique, using the more durable glue, could be adapted to make strong, light, boats.

Faireys method was somewhat similar to the “vacuum bagging” method used with cold moulding today, but Faireys method was rather more drastic – the hull was laid up over a male mould, using a system of pre-fitted slats, rather than staples, to hold the veneers in place. It was then covered with a fitted rubber sheet and steam was injected into the autoclave to give a pressure of 50psi at 100 degrees C which was maintained for 12 hours.

The Firefly, a modification by Uffa Fox and, we think, some of Faireys staff, of a pre-War clinker design by Uffa Fox for a “Cambridge University 12 footer”, a design to the National 12 rule but modified to be easier for a beginner to sail than the “Uffa King” National 12 design, was the first boat built by the hot moulding process. The 14ft Gannet and theSwordfish, a 15 foot dinghy on somewhat similar lines, followed but were much less popular.

Early examples of the Firefly, up to hull number 650 (and the Swordfish?) were hot moulded from three skins of 1/16″ birch plywood, like the WW2 aircraft. Indeed, the birch plywood was “War Surplus”, which is why it was available at all in post-War Britain. The resulting hulls did not look espescially pretty, and were painted. It is not thought that many of these survive now. From approximately Hull 650 onwards, Faireys substituted three skins of agba veneer for the birch plywood; this proved much more durable, but they continued to paint the hulls. Some owners scraped the paint off and varnished their boats; this persuaded Faireys to do the same. From hull number 2,900 (for Fireflies) Faireys laid up the outer veneer on Albacores and Fireflies fore and aft, raher than diagonally.

It has been found, over the intervening sixty years and more, that hot moulded agba is a very durable hull material indeed.

At the instigation of several members of Lock SC, Faireys modified the Swordfish design to produce the Albacore, a simpler, lighter, cheaper dinghy with more freeboard, which sold well.

The 18ft Jolly Boat, designed by Uffa Fox, was the largest planing dinghy produced by the hot moulding method and was for some years the fastest dinghy in the world.

The Faireys-built Finn, International 14, 505 and Flying Dutchman are comparatively rare and should be sought out and restored if at all possible. Only one Gannet is known to exist.

Most hot moulded hulls have the outer skin of veneer laid diagonally, but, in the 1960s, Faireys’ staff modified the production process for Fireflies and Albacores so that the outer skin was laid fore and aft; these boats look particularly attractive when varnished.

Repair methods and materials:

Since a private owner is most unlikely to own an autoclave, repairs must be made using “cold moulding” techniques.

Fortunately, glue technology has advanced, so a cold moulded repair using modern epoxy glue should be as strong and durable as the original hot moulded hull.

Materials:

The raw materials are therefore agba veneers and epoxy glue – Agba veneers can be had from Robbins Timber in Bristol
http://www.robbins.co.uk/marine/prices.asp and marine epoxy and fillers, either SP or WEST, can be obtained from most chandlers.

Tools and Equipment:

You need a staple gun, (from a good tool merchant), staples of various lengths (ditto), something to staple through in order to pull the staples out after the glue has dried (old toe straps are excellent for this) a sharp knife, a straight edge, a bevel gauge, a pair of dividers, something to mask areas from epoxy (brown parcel tape and polyethylene sheet do well) and some thin plywood (obtainable from model shops) along with some softwood and the usual woodworking hand tools if you need to make a former to laminate over to fill a big hole.

You also need a dry, reasonably warm (10deg +) working area, ideally with electricity laid on.

Because boats are symmetrical in one plane about the centreline, where a hull is badly damaged, the intact half of the hull can serve as a pattern for any missing areas.

Typical areas of damage:

Damage may occur when sailing or when not! In particular, when left in a dinghy park with the mast up under a boom up cover, rain will run down the luff groove of the mast in quite remarkable quantities and sit in a puddle on the bottom of the boat.

The Firefly in particular is often seen in dinghy parks with her nose in the air so that water running into the boat down the mast groove can run out through the transom drain holes; unfortunately a drip of water remains inside the boat, and the aft end of the hog is in contact with the damp ground, creating ideal conditions for wet rot.

The forefoot area gets clobbered in getting the boat on and off her launching trolley and once the varnish is damaged water gets under it.

Built in tanks are attached with brass screws through the laminated skin and urea formadeyde glue; the area round the screw head often goes black and mushy.

The biggest problem area is the hog and centrecase area. Water collects in a puddle at the bottom of the boat and eventually the centrecase and the hog rot out… centrecase replacements are not unusual and in the case of the Firefly Ray Smith at Tomato Boats in West Mersea [url]tomatoboats@btopenworld.com[/url] sells pre-cut centrecase sides.

Water in a puddle at the bottom of the boat can get into the hog to planking join and enter the end grain of the agba laminates; weakening of the bottom of the hull can result in a human foot going straight through it and from time to time dinghies are impaled on trolleys, edges of hards, submerged posts, and so on resulting in dramatic looking holes in the boat.

Boats (most of them!) with built in buoyancy tanks are prone to failure of the urea formaldehyde glue in way of the glues and screwed bulkhead, tank face and tank top to moulded hull connections; this causes the tank to fill with water during a capsize and to stay that way afterwards, trapping water and promoting rot.

The plywood decks do not last anything like as long as the rest of the boat, and re-decking every few years should be considered routine.

“Mark 2″ Fireflies with laminated gunwales are prone to delamination of the gunwales, which are glued up with urea formaldehyde; if these go the whole boat starts to resemble a banana and the resultant flexing splits the bouyancy tank to hull joins (see above).

All of these are fixable.”

Ed’s view:

Materials:

The raw materials for working on Fairey Moulded Veneer hulls are: some thin wood veneers and ply (preferably Agba) and some glue epoxy works well, but so does a slow polyurethane foaming glue. Agba veneers (and others) can be had from Robbins Timber in Bristol
http://www.robbins.co.uk/marine/prices.asp and a good epoxy and some fillers (Sicomen, Sp or West to taste) are widely available.
The wood:
The first problem you bounce into is likely to be the veneers that you can get hold of. The agba from Robbins is variable in quality, some can be quite dry and well cracked. More importantly, it is nearly always only available in one thickness of 1.5-2mm which is really too thin for working on fairey boats which are nominally made out of 2.5mm veneer. But of course, you only need the Agba for the outer layers and I would normally advise using standard mahogany building veneer (or even thin ply – marine or modelling) for the middle layer, which is normally available in something closer to 2.5 (2-3mm). Because wood varies so much, I really think nothing beats actually going up to Robbins (or other woodyard) and picking out your own leaves of veneer. That way you at least know what you are getting. Leafs normally are about 6-8ft by 8-12in and will roll into a circle of about 1-1.5m depending on how dry they are. So with luck you can get them in the back of the car.

The Glue
I think my preference is to work with Epoxy, but there is really no reason why you can’t use other good boat-glues. I have had sucess with foaming polyurethane when I wanted to work fast, or indeed if there are any gaps in the join as it is very good at low-strength gap-filling. Just be very careful if you use the ‘quick’ version (which to be honest is normally ‘why’ you are using the glue in the first place, unless you like to totally blacken your hands for the fun of it) as the foaming can produce enough push to lift the veneer if you are not careful. On the other hand, as I said, it does nicely fill up any voids that you might have.

Tools and Equipment:

You need a staple gun, normally the ones that take the small staples rather than the big ones, which leave bloody great holes, (from a good tool merchant), staples of various lengths (ditto), something to staple through in order to pull the staples out after the glue has dried (old toe straps are excellent for this) a sharp stanley knife, a set of sharp chisels, a small low-angle hand-plane, various sanding blocks, a straight edge rule (longer than the hole you are filling), a bevel gauge, a pair of dividers, something to mask areas from epoxy (brown parcel tape and polyethylene sheet do well) and some thin plywood (obtainable from model shops) along with some softwood and the usual woodworking hand tools if you need to make a former to laminate over to fill a big hole.

You also need a dry, reasonably warm (10deg +) working area, ideally with electricity laid on.

Because boats are symmetrical in one plane about the centreline, where a hull is badly damaged, the intact half of the hull may serve as a pattern for any missing areas, but to be honest, they are also ‘handed’ so I have had better luck using another section of the ‘same side’ of the hull.

The damage:

There are various types of damage that you might have:

Crash damage – Small
Crash damage – large
Rot damage – Small
Rot damage – large

Doing big holes can start to get hard if they curve of the hull is bending substantially in ‘two’ dimensions at once and will mean that you need to build a former or mould to build onto, but to be honest, I will only do this if I really have to and you will be surprised by how much you can do without a former.

So, for the moment, I will leave the big holes and concentrate on the smaller holes.

I would call ‘small’ anything from nail-hole size to about 6-9in square in which the curve of hull is only turning in one direction.

First, you have to remove all broken or rotten wood.

This is easier with rot damage, simply because the wood is softer.

You just hack and pull away until you have removed all loose or soft wood. Then you can see how bad the situation is. If you started this to try and fix a baby bit of rot, what you thought was the size of a finger is now the size of the palm of your hand. Take a deep sigh and go and have a pint of beer or sleep on it, it will look better later. It is still likely to get bigger before you start fixing it.

Your hole is now a weird shape and the first thing you have to do is to clean up the edges. You don’t just get a jig-saw!

you need to draw a patch that is the shape of a square, oblong or parallelogram around the damage giving on average about half an inch or so gap around the damage. Look at the lines of the veneer and draw a line around the damage that is ‘inline’ with the lie of the veneer in one direction and then a straight line across to the other side, thereby creating a drawn patch that is somewhere between a square and a parellelogram. This shape has to go around the whole damage.

Then using the stanley cut through the top veneer all along this line around the hole. Once you have done this go around with a sharp chisel and chip off the outer layer of veneer back to the line you cut with the stanley. When you have finished you will have an irregular hole surrounded by a regular cut shape in the outer veneer.

When finished, do the same thing on the other (inner) side. The inner and outer shape do not (should not) be the same.

Rupert’s view:

Seems to me we got to the stage of having 2 rectangles (one inside, one out) a veneer width thick, with an irreegular hole in the middle. At this point I would ensure that there really is no more rot in the middle layer – it spreads further inside than outside.

What you should have bought before this is some veneer (Robbins in Bristol sell it, dunno who else) some epoxy and filler powders (plenty on this elsewhere – you want sandable filler powder, though, not rock hard stuff) or you can use foaming glue (Balcotan) or Cascophen, which is the nearest to the original glue. If in doubt, go with epoxy. You will find a staple gun rather useful at this point, too. I’ve heard great things about plastic staples, but I’ve not used them. Each staple will need something under it so you can pull them out.

using the paper template you used for the hull cutouts, make a plywood patch. Others may disagree, but where both sides are accessable, I would do the outside first, as it is easier to bend round the outer curve without support. Test fit the veneer, then make another one which actually fits. Funny how that happens… Tape up the wood round the job to stop the glue from spreading toooo far.

Mix the glue, spread on the boat. fit the top edge of veneer, and staple. If you staple too near the edge of the hole, the middle veneer will split. Too near the edge of the patch, that will split. The patch that fitted perfectly still does, I hope! Bend the veneer into place, putting staples in to hold it. Once it is in, wipe away excess glue from the job, crawl under the boat and clean up the inside, too.
That is the outer veneer on. Take staples out when it has gone off. Surforms are good for removing excess glue, if you are careful.

Mungo’s view:
 
I can offer a naive perspective…. more where I found things difficult. Given my experience with this I’m not sure I’m a good source of info. Also take it with a grain of salt my experience with wood consists of poorly sharpened pencils. My biggest patch is only about 3X5 inches and I always had at least one layer of veneer to help shape the patch. Others will be able to offer better solutions. I have pictures of my attempts I would be glad to forward. There is a lot of info on the forum but it is actually not that easy to find. Searching by boat name (Vivette? Garry’s boat??) or firefly works better than veneers etc. Would be nice if someone who did this well would go point by point with pictures.

My chimp like approach…

I traced the area I was going to cut with pencil, then outlined it with masking tape. Somehow I thought having the tape would help with whatever obsessive compulsive psychosis I harbour, but it was a dumb idea when I removed the tape it sort pulled bits off the cut edges. I used a flexible steel ruler and a razor knife to make the cuts. Where the curves are tight this method sucks and just slow and steady freehand is probably better. I put a small mark on the knife blade so I wouldn’t cut too deep when I was trimming the inner veneer. The wood has varying density so it cuts easy then gets difficult etc, easy to suddenly cut to far especially with the grain of the wood. Lots of very shallow strokes worked best for me. I found that in areas of rot that a small piece on an outer veneer expanded a lot further in the inner veneer. A sharp chisel removes the veneer layers cleanly and easily. I found the boat wood much harder than the replacement veneer.

I practiced with some thick card and found that in the curved areas of the hull it was quite difficult to measure the size of the patching veneer. My simian solution… I rubbed the edge of the cutout with a soft pencil then placed thick card over the area and rubbed around the edges transferring the shape to the card. I cut that shape out, tried it as a patch, then traced it 1 mm bigger onto the veneer. I cut that out and slowly fit it to shape. Biggest problem was bending the veneer around the curve. I had a quite small piece and it did not like bending. This made trimming difficult as I would get one edge aligned but holding it down to measure the opposite edge was almost impossible. The veneer cuts nicely across the grain but it is easy to go astray with the grain, even small wobbles look much bigger after being glued. One of the veneers had a defect that only came out when I sanded it. Just a small empty space that I will fill with epoxy. Might want to check your veneers carefully, although I don’t think I would have seen it.

On my boat the hull veneers vary in thickness quite a lot and for one area the veneer I used to patch was not thick enough to be flush. I used very thick epoxy paste to fill below the veneer, I was careful that this was placed between thin epoxy so it bonds well. This might be a dumbass solution as it was difficult to align the replacement veneer and when stapled glue leaked everywhere. In the end that patch looks pretty crude. Maybe modeling ply that comes as thin as 1/32 would help??

I used West epoxy and it is a lot thinner than my previous experience (system 3). I didn’t like the water like consistency so I thickened it slightly with a bit of agba flour made from sanding the cut out bits. This resulted in the edges of my patches being outlined as the wood flour makes the glue darker than the wood. These might blend in more once sanded flat and varnished. I painted unthinned epoxy on both the cutout and the veneer, somewhat liberally as the veneer is quite thirsty. I then used a bit of the slightly thickened epoxy in the cutout, put the veneer down, put waxed paper over most of it and stapled it with 1/4 inch staples over baling twine (makes them easy to remove), I think I was over enthusiastic with the staples. I used a slow hardener so I left it for 3-4 hours, then scraped any glue that was leaking out the edges away using a razor blade. I left it overnight before removing staples. On the curved part of the hull I found this hard, the glue gets all over as I tried to bend the veneer. I tried stapling an edge before bending but the veneer cracked and I had to cut another (the advantages of slow hardener). By the time I got the patch in place I had sort of mangled the nice sharp edges I had cut. I suspect there is a trick here and maybe someone else has a better way of bending veneer across the grain. Making the patch bigger in this area would help. I did one veneer layer at a time, gluing the second layer as soon as the first was dry enough to hold. Not sure if modern epoxy blushes but I glued before it would anyway.

I found aligning wood grain quite difficult. I thought I did a good job and after it was done it’s off by a few degrees, then again it’s wood. I picked a veneer that matched the hull colour nicely, then when I sanded it it came out much lighter than the hull. Due to the shape of the hull one of my patches has rather acute angles at the corners. I think I would have cut these off as they were a pain to hold down and I think they look odd. Stapling was also an issue. Unless the stapler is help perpendicular it shifts the veneer slightly. Once glue is on the veneers they shift easily. Just have to be careful (an observation made in hindsight).

I don’t think it is hard, but one would get better with practice. I wasn’t that happy with my patches as I had dreams of invisible edges but after the wrestling to get the veneer to bend it wasn’t going to happen. I was surprised that even in areas where the edges butt together closely the join is very visible. The difference in the wood colour also really makes them stand out. While structurally sound they are likely crude compared to others and once I sand the hull I shall see what they look like. I found it quite satisfying, you go from a hole to a smooth hull. I found it difficult to cut into the hull, I contemplated those masking tape squares for quite a while, looked at my poorly sharpened pencils, the squares… red wine helps overcome insecurities about future incompetence. Vinegar removes epoxy fingerprints from wine glasses.

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