Centerboard 28' CK

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Centerboard 28' CK

Postby eodguy » Tue Nov 21, 2017 3:00 pm

Do any of you 28 Cat Ketch owners know the weight and composition of the centerboard?
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Re: Centerboard 28' CK

Postby Goose13 » Tue Nov 21, 2017 10:07 pm

I have a 33CK CB and it supposedly weighs 800lbs but I've also seen that it may be 1200lbs, it is also supposedly lead surrounded by fiberglass. Hope that helps.
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Re: Centerboard 28' CK

Postby andygc » Wed Nov 22, 2017 6:36 am

Yes. It is a glassfibre foil section moulding weighted with lead shot. Mine weighs approximately half a ton. Handle with great care.
Feronia
(UK Freedom 30 cat ketch, build number 107)
River Exe, Devon
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Re: Centerboard 28' CK

Postby eodguy » Wed Nov 22, 2017 4:07 pm

Thank you both.
I need to repair the deck around the turning block so I think I'll rest the board on the bottom. Should be about 2.5' of water below the hull at my dock.
Had considered slinging it with a line around the boat but too much weight.
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Re: Centerboard 28' CK

Postby andygc » Thu Nov 23, 2017 10:45 am

You could certainly tie a sling around the boat. A single length of 12mm rope towards the back end of the keel would have no problem supporting the plate. You are looking at rope with a breaking strain of 3,000kg supporting no more than half the weight of a no more than 500kg plate which is at least half immersed in water (so reducing the weight to be supported).

Alternatively, you could look on this as an opportunity to check the state of the lifting tackle. You can unscrew the table top and lift it up. Then you can unscrew the top cover of the trunk and lift that up. You can then support the plate, partly lowered, by a length of rope through the lifting eye (12mm is more than strong enough), tied round a stout wooden bar across the slot. Once that takes the load you can unreeve the uphaul, allowing you to then remove the grab tube and turning block (which are attached by the same bolts), the top cover and the table top. You can then check over the pulleys. I needed to replace the bronze sheave in one of the fixed blocks, have another sheave drilled and bushed, and replace the double block with becket that's attached to the lifting eye. You can also check the limit strop, which stops the plate going down too far - it should be just slack with the plate fully up.

When I said handle with great care I meant when you have just craned the boat off the plate with the aid of a lump hammer and a few oaths, and with the boat ashore. It would be very easy to drop it onto somebody's leg. ;)

I wouldn't want to rest the centreboard on the bottom. What might happen in stormy weather?
Feronia
(UK Freedom 30 cat ketch, build number 107)
River Exe, Devon
andygc
 
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Re: Centerboard 28' CK

Postby eodguy » Fri Nov 24, 2017 1:54 pm

Wow, great description Andy!
Would you happen to have a drawing and specs of the lifting mechanism/trunk/table assembly?
My thoughts on resting the board on the bottom stem from being in very sheltered water (dead end a canal off the Banana River on Florida's Space Coast (Brevard County)) and we see very little water movement even during storms and no tidal action. I plan to do the other deck repairs first in order to get the learning curve for this job out of the way (I've done plenty of glass work) and limit the time the board would be down to a day.
One second thought, I'm going to need to have the boat hauled for bottom paint and can do it with the boat on the hard. The yard I use allows 5 days of work with a haul out and bottom job.
Thanks for the help.
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Re: Centerboard 28' CK

Postby andygc » Mon Nov 27, 2017 5:48 am

Pictures, but not all the details. General arrangement looking forward, plate removed. The eye on the left is for the fixed end of the limit strop. The sides and ends of the table casing are removed - the plate cannot be removed without drawing bolts from the sides and front of the centreplate trunk.
DSCN0281.JPG
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Internal view of the front end of the trunk. The saddle that holds the hinge pin is lower than when fitted - the horizontal piece would be level with the top of the trunk. The sunbeams are shining through the hole the uphaul comes down through. Note six bolt holes for pulleys.
DSCN0282.JPG
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How the pulleys are arranged when fitted.
DSCN0290.JPG
DSCN0290.JPG (132.12 KiB) Viewed 85 times
More pictures to follow.
Feronia
(UK Freedom 30 cat ketch, build number 107)
River Exe, Devon
andygc
 
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Re: Centerboard 28' CK

Postby andygc » Mon Nov 27, 2017 5:54 am

The centreplate. Note that this shows it at an angle lowered a little beyond the fully down position.

DSCN0274.JPG
DSCN0274.JPG (158.13 KiB) Viewed 85 times


The lifting eye. The uphaul block goes on the forward (right) part, the limit strop goes through the aft (left) part. All the strop needs is a stopper knot each end - nothing fancier.

DSCN0273.JPG
DSCN0273.JPG (101.09 KiB) Viewed 85 times
Feronia
(UK Freedom 30 cat ketch, build number 107)
River Exe, Devon
andygc
 
Posts: 40
Joined: Sun Jul 31, 2016 4:33 pm

Re: Centerboard 28' CK

Postby eodguy » Tue Nov 28, 2017 4:20 pm

Thank you Andy!
I'm sure I'll be back with more questions later.
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