Trotter Keel Case Replacement and Shaping of Centre Board

jamesw
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Postby jamesw » Fri Aug 14, 2009 10:26 am

no no - I comply with the rules - it's 5 litres
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Postby jamesw » Fri Aug 14, 2009 12:00 pm

carefully measured I hasten to add!

when you get your 550 rudder take some pics it'd be interesting to see what it looks like.

btw how much? the 650 dagger rudder costs about $500 plus delivery.
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peter connor
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Postby peter connor » Fri Aug 14, 2009 4:34 pm

Thats great advice James.

I can now take 10 litres out of the 15l tank that we carried around full last year.

Thats the problem when you plan for a cruise the weekend before the Nationals that gets cancelled due to bad weather.

There goes a few kilograms.

Regards

Peter Connor
C18/370
The Smooth

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Postby jamesw » Fri Aug 14, 2009 4:49 pm

remember though that you need a proper anchor - 8S I think with ten metres of chain and 50 of line.
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Postby peter connor » Fri Aug 14, 2009 6:29 pm

James

I'm not falling for that one.

Yes I have an anchor, in fact for the Saturday races last year we still had the aft anchor on board.

10m of chain should read 4m, but thinking about it ,10m would help get the nose down, transom up. HMMMMMM.

We have 50m of rope on the anchor, one day that will be long enough to lasso Katrina.

Regards

Peter Connor
C18/370
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jamesw
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Postby jamesw » Fri Aug 14, 2009 9:11 pm

HAHA you'll have to get close enough to throw it first !!! But, the way things are going it'll not be us you'll be trying to catch.
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paul trotter
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James with Rope

Postby paul trotter » Fri Aug 14, 2009 10:08 pm

But James you are a self confessed bad starter! You just throw the rope over with two minutes to go while your miles away from the line and half the fleet is with you!

I'm confused about the rudder 550 / 650 its just gotta fit a careel. I have given him all the dimensions so I will check.

Yes its $570 plus freight!

Its gunna break me!
Paul Trotter
Nellie C18/472
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jamesw
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Postby jamesw » Sat Aug 15, 2009 6:35 am

Sounds very good. The 650 dagger is really too big but because its shape is nice it doesn't seem to make much difference. The 550 should be perfect and the price is very good, you wouldn't be able to do it yourself cheaper. I bought my 650 rudder simply because it was available second hand. Sheavsey has one on his 22 now and I think he's quite happy with it.

I've been making a rudder stock (won't go into too much detail of course) but just the 6mm allum plate cost $60 then there's been a lot of angle grinding and I'm still waiting to get it welded.

Just don't hassle the Yachtworks guys. You HAVE to pay your money and wait, they'll deliver in good time. People have got stroppy with them over Castle orders and have been bumped to the bottom of the queue (ie from one or two months out to three years out!!).
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paul trotter
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Great Tip James

Postby paul trotter » Sat Aug 15, 2009 7:39 pm

James,

I alway try to be nice but thanks for the advice! I will clarify which number he is making up but it sounds good either way!

Today I again made good progress with the keel.

Both sides now have the 4mm ply glued on and the hardwood leading and trailing edges are now epifilled into position with bricks all over it and gramps in everyknown position.

Tomorrow lunch time I will take it all apart and start shaping which should be very exciting!

I spent this afternoon measuring and remeasuring the keel case. I have 24mm max width to work with. The keel plate is between 14 to 12mm thick and I have clued 4mm ply each side so I already have 20 -22mm which doesn't leave much room for the fibreglass skin. If I stuff this up everything will go bad very quickly!

Cheers
Paul Trotter
Nellie C18/472
Vice Commodore North CCYA

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Postby jamesw » Sat Aug 15, 2009 8:51 pm

nah, you'll just have a keel version - stripe under the mainsail emblem and big handicap - you'll need a tall trailer too!!

i'll have a chat with Greg the handicapper, you'll be fine - can sail against the pyjama stripes boat!!
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Postby jamesw » Sun Aug 16, 2009 7:00 am

Just remembered, Neil Tribe who owned/raced an 18 before moving onto a 22 said to me once that someone had carefully measured the centreboard slot and decided that 25mm was good, made up a new centreboard and it didn't fit.

I think the problem was that while the gap was 25mm it wasn't constant and square.

Didn't Peter Connor make up a dummy ply cb to see if it'd fit.
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paul trotter
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Too close to call

Postby paul trotter » Sun Aug 16, 2009 7:43 pm

James,

I suspect you are right and you are scaring me a bit.

I have had a metal spirit level out that is 23mm wide and it can be manouvred all around the keel case easily. I also taped on a couple 2mm Paddle pop sticks and it doesn't move. Then I attached some hack saw blades at 0.5mm and they still work.

I think I have got 24mm to play with and thats it!

More good progress was made today. The last layers of glass were glued along the keel case at the false floor to ensure it is all stiff enough. That all went well after some initial sanding to smooth out.

The exciting bit came after lunch. The keel ply had 24 hours to cure so all the weights and cramps came off and it looked magnificent with the spotted gum leading and trailing edges bonding nicely to the keel.

Out came the orbital sander with some very rough paper and away I went. Not before I made up a template out of ply to ensure I got the correct aerofoil shape at the leading edge. I have it tapering back 150mm.

The sanding went well and I tested the top of the board. First doing the leading edge and then the trailing edge. She sanded back nicely and already looks and feels fast. I used a straight edget to check my depth of sanding along the front edge. I need 8mm clearance to avoid the keel projecting beyond the hull line. So I am sanding back to 6mm and will then apply about three sheets of glass on the leading edge and that should build it out close to 8mm again.

The rest of the upside face of the keel ply was then sanded back and I mananged to sand all the leading edge and bottom and most of the trailing edge. It looks brilliant. Before finishing for the night I mixed up some more Epifill and then went over the keel filling up any more gaps and building up the bottom edge to acheive a curve and streamlined bottom. The tailing edge of timber also needed a little more bog where it meets the keel.

While I was covered with sawdust the result looks outstanding.

Next weekend I will attack the other side with the sander, coat one side with Epidure to protect the ply and attempt to get the fibreglass laid on one or both sides. Its a big effort and my wife Mary is lossing patience with my obsession!

I'l try and post some pictures. It looks like I have succeeded. As you can see this is the result at the end of the day. The white stuff around the perimeter is the Epiglue I have used to bog up holes / depressions all around the edge and I left it tonight to cure. The clamp is holding a little peice of ply that delaminated at the top. There needs to be more ply shaved off the trailing edge but this will take some time next Saturday.

The shot below is how she looked before all the weights and clamps came off!
Attachments
Keel2.JPG
Keel2.JPG (320.49 KiB) Viewed 3251 times
keel.JPG
keel.JPG (235.72 KiB) Viewed 3254 times
Paul Trotter
Nellie C18/472
Vice Commodore North CCYA

don47
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Postby don47 » Sun Aug 16, 2009 10:12 pm

TROTTS.

Your CB works sure do brings back some memories of a year ago for me . Looks like she's coming along fine so far, it's a bit of job alright , however the end result will make it all worth while.
Don.

peter connor
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Postby peter connor » Mon Aug 17, 2009 9:53 am

Paul

Keep up the hard work.

As for a template Centreboard, I did make one, but it wasn't to check board clearance on the sides of the case. It was to check the keel slot closer I now use.

I have a 3/4 inch plate board, so it was always going to fit.

As for glassing, when I have made timber centreboards in the past, I have always glassed the first side before I profile the second. It stops the aft tapered edge of the centreboard from curling over when you plane it to a fine edge, giving the timber extra support stops it curling over under the weight of the wet resin and cloth. It may not be such a problem with yours depending how fine the taper is.

Regards

Peter Connor
C18/370
The Smooth

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Trot's keel case repair

Postby Luna-C » Mon Aug 17, 2009 5:22 pm

Hi Paul...

Just a BTW... in case you dont already know...

Those nylony plastic shims that sit between the keel and the casing are actually made from a special water lubricated plastic ( ascorbic is the term I think)called "Delrin" or Acetal... very expensive stuff unless you can manage to get some offcuts... If needs be the agents for the Delrin plastic are at Archerfield but cant remember the name of the place... If you get stuck, I have some 5mm Delrin left over from when I had to rebuild my keel housing a few years back...

If however you only have a few mil clearance in the keel housing, you may be in strife as those shims are a must unless you want to repair the inside of the keel casing next time...

cheers,
Marc
(aka Luna-C)


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