Re decking a 1957 Finn

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Finnsailor
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Re decking a 1957 Finn

Post by Finnsailor » Sun Jan 27, 2013 1:02 pm

Any tips much appreciated.

I am just about to put the new 3mm ply deck on my Finn, but I seek help and advice from those who have done it before. I intend to put the sheets of ply on the crossmembers with each sheet covering about a quarter of the deck.

My intention is to glue the sheets to the crossmembers using epoxy, no tacks, but bags of sand to hold each sheet down. My 2 big questions are:-

What type of saw to use to get the best cut?

What type of joint, can I just butt or do I need to overlap the sheets having removed 1.5mm from top and bottom sheet?

Any advice gratefully recieved before I start.

Many thanks

Martin
Martin
1957 Jeremy Rogers Finn K192
2004 modern Devoti Finn: GBR567

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PeterV
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Re: Re decking a 1957 Finn

Post by PeterV » Sun Jan 27, 2013 1:38 pm

Martin,
When I did the foredeck on Django I just butted up the cut edge of the sheet down the centre of the king plank. I cut the edge out roughly leaving about an inch overlap then planed the edge down once it was all set. I epoxied the deck on like you propose but added a few pins where I didn't have enough weights. I didn't get a perfect fit around the gunwales but that's more because I reused the old ones so they were a little damaged. On Django the foredeck ends at the front of the cockpit where I had to taper the deck down to merge into the side tanks which they overlap in parts. The butt joint on the centreline looks fine, but you'll also have one on each side deck. On my Enterprise these were also butt joints just aft of the shrouds and they looked fine.
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neil
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Re: Re decking a 1957 Finn

Post by neil » Sun Jan 27, 2013 2:49 pm

I would have thought that 3mm would be on the thin side, presumably the side decks and rear tank have plenty of reinforcement.

when I did the Tideway used all my clamps, plus load of bags of sand. Put the decks on oversized and planed them down before putting the gunnels on.

Butt joints are fine with decks, make the butt joint on a frame so it's not floating between frames.
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PeterV
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Re: Re decking a 1957 Finn

Post by PeterV » Sun Jan 27, 2013 4:50 pm

Django is 4mm Robbins elite, which is light but also pretty weak. I've stood on the foredeck many times but I am careful not to put my weight on one knee.
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Finnsailor
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Re: Re decking a 1957 Finn

Post by Finnsailor » Sun Jan 27, 2013 5:29 pm

Thank you both, I am not worried about the decks being lightweight, I have no intention of standing on the deck, - it might ruin the varnish! I am pleased to hear the butt joint will suffice, but what is the best tool/saw to use to ensure the cut is straight true and will line up? This is my biggest worry, getting straight edges that will butt together.
Martin
1957 Jeremy Rogers Finn K192
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Ed
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Re: Re decking a 1957 Finn

Post by Ed » Sun Jan 27, 2013 6:26 pm

the saw isn't going to make much difference.

I normally use a good jig-saw.

but a really good, sharp and long jointing plane will be what you need to get a good join. Then cut a line with a sharp Stanley blade from a good straight edge and plane the edges with an ever-so slight undercut so there is no danger of pushing out all the glue from the joint (presuming you are using epoxy).

However good your original cut-lines are, the chances will be that you need to take a shave here or there to get it quite right.

I'm with Neil....I think 3mm is a bit thin, unless there is plenty of superstructure underneath. I know some Finns are like that. Mine K465 was decked in two 1.5-2.0 mm layers of veneer, but this was over a very substantial superstructure, with supports every 6in or so. I havn't seen this in older Finns? But I am by no means a Finn expert.

cheers

eib
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neil
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Re: Re decking a 1957 Finn

Post by neil » Sun Jan 27, 2013 6:37 pm

There is no single tool that will give the perfect straight cut (at least not in the usual workshop/garage setup). It will be down to you using a saw of choice to get as close to the cut line as you dare then use a plane to get the straight edge.

I use a jigsaw for longer cuts (with a fine blade for ply), but have a pair of Japanese pull saws for anything less than about a foot. Then its a case of a very sharp plane until you get the straight edge. You can also make a sanding bar by gluing the paper to a piece of hard wood and use this on your cut edge.
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PeterV
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Re: Re decking a 1957 Finn

Post by PeterV » Sun Jan 27, 2013 7:23 pm

If you can't stand on the foredeck then you're unable to take part in downwind races standing in front of the mast. It's the only race where I managed to beat Chris Law and David Howlett, and it was David's idea! I had an advantage as its the type of thing we used to do often during the summer holidays. An essential part of Finn sailing I thought!
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poacher
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Re: Re decking a 1957 Finn

Post by poacher » Mon Jan 28, 2013 10:22 am

Martin
Use a steel straight edge and a new Stanley knife blade, this cuts cleanly and does not split the veneer. Do not cut square ( ie at 90 degrees ) but at about 60 degrees of undercut as this allows for plenty of epoxy supporting the joint.
See you in the racing boat next season.
John

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Ed
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Re: Re decking a 1957 Finn

Post by Ed » Mon Jan 28, 2013 1:49 pm

Well, we all pretty much agree then!

:D :) :D
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davidh
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Re: Re decking a 1957 Finn

Post by davidh » Mon Jan 28, 2013 4:11 pm

When we redid the foredeck on the contender, an 8x4 sheet of ply came up about 2 1/2" short of following the curvature from gunwale to gunwale. The purist way to address this would be be buy 2 sheets and then go for the classic butt joint up along the centreline. However, Ian Ridge did a stunning job of adding in a small triangle that just allowed the deck to be laid from a single sheet. It was laid using large sacks of damp builders onto a plentyiful supply of epoxy.

Unless you already have a raised centre spine on the foredeck it might be worth looking at the options of doing it in one!

D
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Re: Re decking a 1957 Finn

Post by fatboyfinn » Mon Jan 28, 2013 4:23 pm

Just to throw a spanner in the works - I used 1.5mm constructional khaya mahogany veneers to deck "Larfinn" K465 and it still seems to look good.
I first laminated the deck beams of Douglas Fir with spruce stringers. Then, glued and stapled ( removed after glueing ) first layer of veneer
in a chevron form facing forward, followed by a second layer again stapled chevrons going aft. One advantage of this method is
its cheapness and lack of waste material. Glue being SP 106 with some colloidal silica.

Andy

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Re: Re decking a 1957 Finn

Post by Finnsailor » Thu Jan 31, 2013 8:32 pm

Thank you all, some sound advice there. The tip about cutting using a sharpe knife is helpful also ensuring there is an undercut to hold extra glue. I will let you know how it goes and try and post some pictures, but you will have to wait till late March, when I hope to be at home long enough to get the job done.

I hope to laminate a rudder from alternate strips of light and dark wood. The whole rudder and tiller must not weigh more then 3.8Kg and covered in epoxy. Any suggestions on the best choice of wood?
Martin
1957 Jeremy Rogers Finn K192
2004 modern Devoti Finn: GBR567

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Re: Re decking a 1957 Finn

Post by Rupert » Thu Jan 31, 2013 8:40 pm

I did as David says (added a tiny triangle in the corner) when doing Saskia the Firefly's decks. I would certainly use this method again.
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PeterV
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Re: Re decking a 1957 Finn

Post by PeterV » Thu Jan 31, 2013 10:19 pm

There's a description on the classic finn site on how I made my rudder from western red cedar. It came out just on 4kg but only with a heavy ash tiller on. It's lasted about 5 years so far so I'm sure it's long enough.
PeterV
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