Athaena - Rot near the chine

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Athaena
Posts: 63
Joined: Wed July 22nd, 2009, 12:36 pm

Athaena - Rot near the chine

Postby Athaena » Sun September 20th, 2009, 7:34 pm

Hi All,

I'll introduce myself first as this is my first post, my name is Chris and I've recently purchased Atheana (featured on various pages here).

Unfortunately I've found a few soft spots in the ply which are going to need dealing with asap. Having read around the best (only) solution seems to be to cut out the rotting timber and a foot or so around and replace with new. However, I would appreciate advice on how this might best be done in the location concerned.

The patch I am most concerned about is just above the chine (Athaena has a single chine) on the starboard side.

The photo below is from the outside. You can see the sink outlet, starboard chine, bilge plate and keel behind. Almost dead centre in the image a small grey cross is scratched to mark the spot.
Image

The next picture is take from the inside and the scratched away area to the left of the bradawl corresponds with the spot marked on the outside of the hull. You can see between the scratched area and the sink outlet is a piece of ply joining two sheets. The sheet to the left as pictured seems solid as does the backing piece.
Image

My problem is that it's not just the ply that is soft, the timber that the bradawl is stuck into has the consistency of cheese! It appears to be a laminated affair built up from several planks (pieces of ply I think), the top facing plank seems sound, but those behind closer to the hull are very soft. Obviously this also needs replacing. It would seem to be an earlier repair as it doesn't match the appearance of the the same chine in the adjoining void immdeiately forward pictured below.
Image

My questions are these:

1. Obviously I need to cut out and replace the hull ply, but how do I "patch" the chine timber?
2. I'm fairly depressed because I thought I had a reasonably sound boat, how much work am I looking at in the big scheme of things?
3. With a longer term view, would it be better to do a major replacement of much of this area now or would a good "patch" last as long as a "big repair", that is what is the most cost effective solution in the longer term?

All advice and encouragement very gratefully received!

Chris

chris s
Posts: 135
Joined: Sun March 5th, 2006, 6:55 pm
Location: Netherlands

Re: Athaena - Rot near the chine

Postby chris s » Mon September 21st, 2009, 9:27 am

Oh Dear, But at least you found it before it found you, if get my drift!

While not being in any way an expert it timber/plywood comstruction I have in the past used this with sucess

http://www.marine-super-store.com/posit ... no=65-1063

Of course the correct way to repair is to cut all the affected wood out and replace it with new.

Athaena
Posts: 63
Joined: Wed July 22nd, 2009, 12:36 pm

Re: Athaena - Rot near the chine

Postby Athaena » Mon September 21st, 2009, 6:37 pm

Thanks Chris, yes I'm pleased (if dissapointed overall) to have at least found it whilst she's on the hard.

I'm afraid the chine is a long way past "git rot" that bit the bradawl is stuck into really is like cheap chedder! To start with I though it was sealant.

The Git rot may well be useful in the rood of the forecabin though where water has leaked down the side of the sansom post and may have gotten into the ply below the teak deck. Just need to work out how to apply the git rot upwards!

If anyone has any experience of replacing sections of the chine and how this might best be done I'd very much appreciate any advice.

Chris

chris s
Posts: 135
Joined: Sun March 5th, 2006, 6:55 pm
Location: Netherlands

Re: Athaena - Rot near the chine

Postby chris s » Mon September 21st, 2009, 8:45 pm

I don't know for sure, but I always thought that the chine rails were solid timber rather than laminated ply? all that exposed end grain just waiting to rot :(

Billaboard
Posts: 25
Joined: Thu October 5th, 2006, 9:48 pm

Re: Athaena - Rot near the chine

Postby Billaboard » Mon September 21st, 2009, 11:46 pm

I don't know if I'll be of much help, but the history of our Wild Duck is that we finished the build and launched onto someone else's mooring in about 1986 and then a couple of months later in a storm the mooring broke and she was driven backwards into a U-shaped recess in the rock sea defences. The rudder took most of the damage, but the port side was stove in and the plywood skin and the chine rail on the port side were badly damaged. We nailed ply patches over the damage and punted along the shore to a boatyard that night on the rising tide.

As far as I remember, we scarfed in replacement stringers and part of the chine rail and, of course, replaced about 2 or 3 large plywood panels, plus part of the cabin sides. I think we will have steamed some of the stringers to roughly the right shape. I can't remember with the chine rail, but presumably we sort of carved it to fit. We will have had some of the original left over building materials around at the time. That repair has been fine.

Then recently a surveyor found soft wood in a frame and a small section of plywood skin on the starboard side, luckily above the waterline. For this we just cut away the problem areas back well beyond the decay and fitted new oak and ply in the normal way with large backing pieces. Everything was well doused in epoxy and screwed up tight. The work was done in the open, with the cover being tied back only during the actual work, and with a fan heater inside and (my favourite) 1 million candle power torches shone on the outside to keep the epoxy nice and comfy while it set.

I don't know if we took pictures of the original repair, but I'll have a look to see if I can find any. I think we may have been too busy panicking and rebuilding to indulge in photography. We built a movable platform alongside the boat to help with access while fitting and pulling panels tight.

We used Git Rot on an earlier rebuild of a GP14 dinghy. It, too has been fine as far as I know. I think we went in from above, though. At the time we had a small child happy to climb into tiny corners for the Dickensian jobs.

We were, and remain, complete amateurs, but it was just a question of getting down and doing it.

Athaena
Posts: 63
Joined: Wed July 22nd, 2009, 12:36 pm

Re: Athaena - Rot near the chine

Postby Athaena » Tue September 22nd, 2009, 8:54 am

chris s wrote:I don't know for sure, but I always thought that the chine rails were solid timber rather than laminated ply? all that exposed end grain just waiting to rot :(


I think that's exactly the problem Chris, it should have been replaced with a nice lump of oak and instead someone's used ply and the inevitable has happened :roll:

Billaboard - thanks, your experiences were reassuring that this isn't the end of the world. I'm also going to be repairing in the open.

When scarfing in oak for the chine I'm not sure I can get a good flat slope and fit precisiely at both ends so I'm thinking I might do some sort of stepped joint which would allow a few mm leeway in the fit at either end. Would this compromise the strength of the chine or would it be fine once it's screwed and epoxied in place? Is it worth running a longer backing piece of oak along the chine to reinforce/brace the repaired area?

Thanks for the help :D

Chris

chris s
Posts: 135
Joined: Sun March 5th, 2006, 6:55 pm
Location: Netherlands

Re: Athaena - Rot near the chine

Postby chris s » Tue September 22nd, 2009, 11:50 am

Billaboard wrote:At the time we had a small child happy to climb into tiny corners for the Dickensian jobs.


I know what its like, You just can't get the staff nowadays! :shock:

Billaboard
Posts: 25
Joined: Thu October 5th, 2006, 9:48 pm

Re: Athaena - Rot near the chine

Postby Billaboard » Thu September 24th, 2009, 5:17 pm

Post modified as per suggestions!

If Chris of Athaena would like to contact me by normal email. I can send him the photos of my last repair.

I now understand that the Outbox on the PM utility here only becomes empty when the recipient reads the message. My lack of understanding caused a bit of a personal PM hiatus. :shock:
Last edited by Billaboard on Fri September 25th, 2009, 5:52 pm, edited 1 time in total.

chris s
Posts: 135
Joined: Sun March 5th, 2006, 6:55 pm
Location: Netherlands

Re: Athaena - Rot near the chine

Postby chris s » Thu September 24th, 2009, 10:15 pm

You can e-mail me at XXXX@gmail.com :D

Athaena
Posts: 63
Joined: Wed July 22nd, 2009, 12:36 pm

Re: Athaena - Rot near the chine

Postby Athaena » Fri September 25th, 2009, 12:15 pm

Billaboard wrote:If Chris of Athaena would like to contact me by normal email


Hi Bill, thanks I will do. I'd suggest editing your message to remove your email address. Spammers have programmes that search the web looking for email addresses and I wouldn't want you getting spammed!

Regards,

Chris

Athaena
Posts: 63
Joined: Wed July 22nd, 2009, 12:36 pm

Re: Athaena - Rot near the chine

Postby Athaena » Fri September 25th, 2009, 12:20 pm

chris s wrote:You can e-mail me at XXXX@gmail.com :D



Thanks Chris, I've noted your email, I'd suggest you remove it from public view too :D

Many many thanks,

Chris

Billaboard
Posts: 25
Joined: Thu October 5th, 2006, 9:48 pm

Re: Athaena - Rot near the chine

Postby Billaboard » Sun September 27th, 2009, 2:52 pm

Sorry about the thrashing about in this thread.
I've now done a small set of pictures with explanatory captions and posted them at

http://picasaweb.google.com/billaboard/Boat#

Even if they don't help much, I think they tell a slightly scary story about our winter repairs in an open boatyard in the 80's, plus one pic of the smaller repair in very exposed open field in Feb '08.

Athaena
Posts: 63
Joined: Wed July 22nd, 2009, 12:36 pm

Re: Athaena - Rot near the chine

Postby Athaena » Sun September 27th, 2009, 11:03 pm

Thanks Bill. They were very very interesting.

That damage puts my soft spots into perspective!! :shock:

Chris

JamesH
Posts: 35
Joined: Mon October 13th, 2008, 11:22 am
Location: Bradford UK

Re: Athaena - Rot near the chine

Postby JamesH » Mon September 28th, 2009, 4:14 pm

Does she have the corner post type chines which the WW does?
If so I can see it being quite a convoluted job to extract the chine without damaging the ply, I suspect ply will be damaged scarfing in a new peice in is surely only way to go. how to do itwith out removing ply and replacing whole bang lot I dont know. scarfs should be 8 to 1 but I guess you could get away with 6 / 1.
Make sure that you go 6" past affected area.
all IMHO of course.
yours James
Hi looking to build an WW!
any thoughts.
Have many of the materials for keel and frame.
Yours James

chris s
Posts: 135
Joined: Sun March 5th, 2006, 6:55 pm
Location: Netherlands

Re: Athaena - Rot near the chine

Postby chris s » Mon September 28th, 2009, 5:03 pm

Athaena wrote:Thanks Bill. They were very very interesting.

That damage puts my soft spots into perspective!! :shock:

Chris


It certainly does! it also shows how emminently repairable a plywood boat is. :D


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