Double-diagonal repairs

[JesseLoynes]

Hello,

I've got some double diag planking to repair/replace this summer, and although I've done enough before to feel confident, I thuoght I'd voice a question here anyway.

"What's the simplest way to replace rotten planking in a d/d hull?" There's almost certainly more rotten damage on the inner layer. She's a traditional build, so would like to maintain that.
As with nearly all things trad boat, I'm sure there are two dozen different methods, all equally "correct". Any suggestions?

Thanks for any new handy hints or advice,

 

[Mirelle]

To the best of my knowledge and belief, there is no simple way!

The only way that I have ever seen or heard of is to strip off all the outer planking to both ends of the suspect part of the inner planking, repair the inner and replace the outer.

Whilst doing this, you may console yourself with two reflections:

1. That the outer planking needed refastening anyway...(if it did, in which case you have had a horrid job getting the old fastenings out!)

2. That if she had been built on the Ashcroft System (fore and aft over diagonal) it would be even worse...

 

[burgundyben]

Agreed, no real other option, I did the bottom of one of mine exactly that way.

Ref your comment about the 'Ashcroft System' (never heard of it), I know of a boat sat in Freebody's yard on the Thames which has outer planks fore and aft and clearly from inside inner planks can be seen to be diag, when was 'Ashcorft System' in use and where?

 

[Mirelle]

I know little about it - there is one boat built that way in our parts - but I understand that it was popular for amateur construction from before WW1 until the later 1930's.

 

[JesseLoynes]

Wow! Could this be a single answer to a question with no dispute?

Thanks for the replies, and info on Ashcroft system. I've usually found a new trick or method for virtually everything each time I've spoken to someone new or started working at a new boatyard or marina.

Thanks again,

 

[burgundyben]

Interesting, the boat I referred to was built France in 1936, Merlin, was owned for 40 years by my friends father, she's now waiting the attention of someone with plenty of cash to pay Freebody to fix her up.

 

[burgundyben]

And I forgot to say, my huntsman has seven hot moulded layers, 6 are on the diagonal and the outer layer is fore and aft, it seems not all Fairey boats were like this but some certainly are.

 

[Mirelle]

And our little Firelfy (F3000, "Skyfly") has one fore and aft skin over two diagonal ones! A few Fireflies are built this way, from what I have heard, two brothers working for Faireys worked out the plank shapes and built them this way.

 

[Mirelle]

Oh, that often happens in this quiet backwater of the YBW empire! You will even find motoryacht owners and sailing boaters on friendly terms, here!

 

[andy_wilson]

Haven't a clue, however, having witnessed a gorgeous d/d wooden boat at Agamemnon Yard with stars apparent when viwed from below, the technique in progress looked like...

Remove all fastenings from outer layer.
Pin thin batten to guide router. Set plunge depth carefully.
Route away until all the crap from the outer layer has gone, then carry on to give working access if the planking below is poor. Allow a good overlap.
Remove fastenings from problem areas in lower layer.
Apply batten to guide router. Set plunge depth carefully.
Route to remove the crap beyond the rotten area, and then to next frame allowing 1/2 frame for fastening.
Remove rotten frame sections.......etc. etc. etc.

As for replacement, I have even less of a clue. I'd consider using 'traditional' epoxy saturation to minimise the chance of a re-match.

Now interested to hear whether I should ever buy a d/d hulled yacht for renovation!!!!!

 

[Forbsie]

[ QUOTE ]
That if she had been built on the Ashcroft System (fore and aft over diagonal) it would be even worse...


[/ QUOTE ]

Oh thanks a lot, Mirelle!!!

I'll sleep really soundly tonight then. /forums/images/graemlins/frown.gif

 

[Forbsie]

If you find yourself coming up to London, stop off in Twickenham where my mate is repairing his d/d workboat at the moment and you can get a good idea of what is involved.

 

[Peterduck]

If the planking has fasteners, there is a good chance that it won't be glued to the layer beneath, which will make life easier. Earlier D/D hulls had a layer of linseed oil- soaked cotton fabric laid between layers. The D/D technique has been very popular in New Zealand since the late nineteenth century. Teamed with the legendary Kauri timber, most of these yachts are still going strong. One of the saw blades provided by Fein for their triangular sanders would be just the ticket for sawing through the planks.
Peter.

 

[JesseLoynes]

Superb,

Thanks for all the replies, and suggestions. I'm happy enough doing the work, and have done similar before, but it's the little hints, such as using a router along a batten, or the Fein tool that are always useful. Tanks again.