Renovating an old wooden sports boat, am I mad?

[Wing Commander]

Quick question, from an engineer and from a keen boater, but having never done any boat building before...

If you are essentially laminating several layers together, on top of each other, how do you consolidate all the layers together without having large air pockets between? If the surface was completely flat, or supported from behind, you could have some large weights on to do it, but these shapes are compound curves with just the ribbing behind.

Thanks, and congratulations on the work so far - looks immense!

[Fishtigua]

There was an article in Wooden Boatbuilder about using an air staple-gun with the setting that leaves the staples standing up 1/4" that could be pulled out with pliers. The guy said it saved him hours of faffing about.

[Huntsman]

Fishtigua said:

There was an article in Wooden Boatbuilder about using an air staple-gun with the setting that leaves the staples standing up 1/4" that could be pulled out with pliers. The guy said it saved him hours of faffing about.

Or you pop the staples in over the top of a match, break the match, pliers and pull.

[tr7v8]

Fishtigua said:

There was an article in Wooden Boatbuilder about using an air staple-gun with the setting that leaves the staples standing up 1/4" that could be pulled out with pliers. The guy said it saved him hours of faffing about.

Or staple through a piece of cardboard or thin plastic, that will give a spacing.

[maser_spyder]

Huntsman said:

Fishtigua said:

There was an article in Wooden Boatbuilder about using an air staple-gun with the setting that leaves the staples standing up 1/4" that could be pulled out with pliers. The guy said it saved him hours of faffing about.

Or you pop the staples in over the top of a match, break the match, pliers and pull.

There's a few other methods;

1) Use metal staples, with some method of removing them. Running a strip of nylon strap (that stuff you use to 'wrap' around boxes), punch staples through that, the layer, and in to the hull. Leave a tail, once set and dried, pull tail to remove staples in a row. Neat and elegant, but a bit fiddly. Nylon strapping won't stick to epoxy so it's easily removable. Car seat belts would do much the same thing.

2) Use small screws, driven through a chunk of wood or plastic to hold in place, then remove after. It'll leave a tiny hole, but epoxy will fill that for the next layer.

3) Vacuum bagging. A little complex, but probably the best overall way to do it. As I understand it, you put the strip in place, cover it with a sheet of plastic, seal all around with duct tape, and fit a powerful vacuum pump to remove the air. This pushes the piece down hard on to the layer below, wait to set, remove plastic (again, doesn't stick to epoxy). This method leaves no holes in the strip so it looks great, but it's very fiddly and time consuming as you have to do it a small bit at a time.

4) My current favourite, nylon brad nails. You need to use a special nylon nail gun and special nylon brad nails. Because they're not metal, they won't rust and you can just leave them in place. Fit piece, knock in a brad nail every 1-2", sand down any that sit proud of the surface before starting the next layer.

Right now, 4) appeals most as being the quickest way, with 2) as a backup for the trickier parts that need moving in to place before setting (and perhaps adjustment).

I've read a forum where a guy managed to cut his ply strips and lay up 3/4 of the hull in about 5 hours. That's really good going. He said the best bit about plastic nails is once they're in, you can immediately start on the next bit, and even the next layer before waiting for it to set, as the nails are more than strong enough to hold it all in place.

With no time constraints, I'd go for 3) at least for the top layer, but I'm not totally sure yet. I'll see how the ply goes on first and then make the call.

[maser_spyder]

Wing Commander said:

Quick question, from an engineer and from a keen boater, but having never done any boat building before...

If you are essentially laminating several layers together, on top of each other, how do you consolidate all the layers together without having large air pockets between? If the surface was completely flat, or supported from behind, you could have some large weights on to do it, but these shapes are compound curves with just the ribbing behind.

Thanks, and congratulations on the work so far - looks immense!

To add to that stuff about fixings, there's a bit more to it.

On the large, flat surfaces (bottom near the transom, for example), you cut your ply in to relatively wide strips, maybe 12-24" wide (you can apparently fit entire sheets of ply at once, but I doubt that'll work single handed), applying a bit at a time. When you get nearer the difficult bendy bits at the front, use thinner strips of maybe 6 or even 2-3" to make sure you get the required bend.

The nails/staples/whatever fixings you use will be enough to hold the strip in place while the epoxy sets. Once the epoxy is hard, the nails/staples are useless and can be removed (if they're metal, you definitely want to take them out otherwise they'll go rusty, leaving nasty stains inside your nice new hull).

To best get the air pockets out, you use plenty of epoxy on each layer and put it on with a notched trowel. Similar to tiling a wall, throw it on, then spread it evenly across the surface with the notched bit making sure all the gaps are filled.

The notches on the spreader I got from West Systems are about 5mm deep, which should give you an idea of how much epoxy you get through on a 7m long boat!

[Wing Commander]

maser_spyder said:

Wing Commander said:

Quick question, from an engineer and from a keen boater, but having never done any boat building before...

If you are essentially laminating several layers together, on top of each other, how do you consolidate all the layers together without having large air pockets between? If the surface was completely flat, or supported from behind, you could have some large weights on to do it, but these shapes are compound curves with just the ribbing behind.

Thanks, and congratulations on the work so far - looks immense!

To add to that stuff about fixings, there's a bit more to it.

On the large, flat surfaces (bottom near the transom, for example), you cut your ply in to relatively wide strips, maybe 12-24" wide (you can apparently fit entire sheets of ply at once, but I doubt that'll work single handed), applying a bit at a time. When you get nearer the difficult bendy bits at the front, use thinner strips of maybe 6 or even 2-3" to make sure you get the required bend.

The nails/staples/whatever fixings you use will be enough to hold the strip in place while the epoxy sets. Once the epoxy is hard, the nails/staples are useless and can be removed (if they're metal, you definitely want to take them out otherwise they'll go rusty, leaving nasty stains inside your nice new hull).

To best get the air pockets out, you use plenty of epoxy on each layer and put it on with a notched trowel. Similar to tiling a wall, throw it on, then spread it evenly across the surface with the notched bit making sure all the gaps are filled.

The notches on the spreader I got from West Systems are about 5mm deep, which should give you an idea of how much epoxy you get through on a 7m long boat!

That's quite interesting and alarming how much resin you will need, as you say! It's a shame that you cannot use something similar to these ( Sheet Metal Fasteners) but obviously these are aimed toward thin metal not thicker wood.

When I was involved in composite construction, always had to consolidate the mouldings as air inclusions were a big no no, and resin could not fill those sorts of gaps!

As an aside, I am also another voter for a marinised V8 on headers

[RichB]

Out if interest, do you use these nails or staples on the final layer too? Doesn't that leave tiny holes all over the mahogany or don't they show after the final varnishing?

[maser_spyder]

RichB said:

Out if interest, do you use these nails or staples on the final layer too? Doesn't that leave tiny holes all over the mahogany or don't they show after the final varnishing?

This is where the 'vacuum bagging' comes in, it leaves no holes at all. Screws will leave small holes too so that's out, the only options might be headless nylon nails or similar, but that involves another, different nail gun (c. £200).

So, final layer, I really don't know yet. I'll get the ply on first and see how it goes, by which time I should have a good idea of how it'll work out.

Realistically, you would probably get away with staples, removing them, and then using coloured wood filler to tidy up the holes before final fairing and varnish. Not totally sure yet though.

[rolando]

You probably know this, but you can make your own filler by mixing sawdust from the wood you're using, in this case mahogany, with epoxy. This will give you as good a match as you could ask for.

[mickrick]

rolando said:

You probably know this, but you can make your own filler by mixing sawdust from the wood you're using, in this case mahogany, with epoxy. This will give you as good a match as you could ask for.

I tried that once, but it didn´t work for me, as the wetted out sawdust is a lot darker in colour.

[rolando]

mickrick said:

rolando said:

You probably know this, but you can make your own filler by mixing sawdust from the wood you're using, in this case mahogany, with epoxy. This will give you as good a match as you could ask for.

I tried that once, but it didn´t work for me, as the wetted out sawdust is a lot darker in colour.

With Aerolite 308, which is damned nearly clear, it's worked OK for me with poplar. It would be interesting to know what mterials you used.

[maser_spyder]

rolando said:

mickrick said:

rolando said:

You probably know this, but you can make your own filler by mixing sawdust from the wood you're using, in this case mahogany, with epoxy. This will give you as good a match as you could ask for.

I tried that once, but it didn´t work for me, as the wetted out sawdust is a lot darker in colour.

With Aerolite 308, which is damned nearly clear, it's worked OK for me with poplar. It would be interesting to know what mterials you used.

Cracking idea, I wouldn't have thought of that. West epoxy is completely clear, so I don't see any reason it wouldn't work other than it would need quite a lot of sawdust for a single pump of the resin. Not impossible though, I could easily run scrap through the belt sander and use the waste canister to collect the dust. Gotta be worth a try, and far easier than matching up filler colours.

[mickrick]

rolando said:

mickrick said:

rolando said:

You probably know this, but you can make your own filler by mixing sawdust from the wood you're using, in this case mahogany, with epoxy. This will give you as good a match as you could ask for.

I tried that once, but it didn´t work for me, as the wetted out sawdust is a lot darker in colour.

With Aerolite 308, which is damned nearly clear, it's worked OK for me with poplar. It would be interesting to know what mterials you used.

I tried it with West System and sawdust from teak. It turned out considerably darker.

[maser_spyder]

mickrick said:

rolando said:

mickrick said:

rolando said:

You probably know this, but you can make your own filler by mixing sawdust from the wood you're using, in this case mahogany, with epoxy. This will give you as good a match as you could ask for.

I tried that once, but it didn´t work for me, as the wetted out sawdust is a lot darker in colour.

With Aerolite 308, which is damned nearly clear, it's worked OK for me with poplar. It would be interesting to know what mterials you used.

I tried it with West System and sawdust from teak. It turned out considerably darker.

Because it was more dense, maybe? I guess it might need a bit of fiddling with the quantities to get a good match.

[Fishtigua]

Or use a different wood/sawdust. I dunno, maybe a mix of cedar for the red and ash to lighten it?

[hidetheelephants]

Plastic nails; every day's a school day. Chocolate teapots must be just around the corner!

[Huntsman]

hidetheelephants said:

Plastic nails; every day's a school day. Chocolate teapots must be just around the corner!

When I did the keel on Playtime I very nearly used engineering plastic bolts, in fact, the only reason I didn't was not a technical reason, but a marketing one, I was quite sure that nobody would ever buy a Fairey boat with plastic keel bolts. The Marelon skin fittings look good.

[maser_spyder]

Huntsman said:

hidetheelephants said:

Plastic nails; every day's a school day. Chocolate teapots must be just around the corner!

When I did the keel on Playtime I very nearly used engineering plastic bolts, in fact, the only reason I didn't was not a technical reason, but a marketing one, I was quite sure that nobody would ever buy a Fairey boat with plastic keel bolts. The Marelon skin fittings look good.

This is the stuff I've been looking at;

http://raptornails.com/

When you think about it, strength aside (although they do seem to have plenty of it), it's a very sensible material for boat building. All the properties of bronze in salt water, but a fraction of the cost.

I would think it's only a matter of time before it becomes heavily used in the boat building industry.

If somebody told you 30 years ago we'd be flying around in plastic planes by the early 2000s, you would have thought them crazy.

[RichB]

maser_spyder said:

If somebody told you 30 years ago we'd be flying around in plastic planes by the early 2000s, you would have thought them crazy.

Glider pilots have been flying plastic planes since the late 60s