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Centreboard slot strips - worth it?


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#1 Fleetwood

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Posted 03 June 2012 - 01:04 AM

I sail a heavy, classic centreboard dinghy (Jubilee) which has a fairly wide gap (1-2cm) between the (SS) centreboard and the hull. I understand that most high performance boats use plastic strips to seal this gap, to improve flow and stop water overflowing the case.
Reading other threads I get the impression that they are a pain to install and don't last very long. As we wet-sail our boats we may not see them for a while if they come loose, which I expect would be much worse than not having them at all. We'd have to antifoul them too.
Does anyone have any (quantitative?) info on how effective they are for flow improvement/speed increase?

#2 Mr. Fixit's brother,, Mr. Fixit

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Posted 03 June 2012 - 01:54 AM

Absolutely worth it. Contact your local sailmaker to meet you at the boat during your next haulout. He can measure and make you a centerboard gasket. You will need a strip of brass or stainless steel quarter oval to attach down each side of the slot. I would recommend going on the 'Flying Scot' website forums and get some info on how they make and install theirs. If you keep the boat in the water you can coat it with bottom paint once installed.

#3 cosmicsedso

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Posted 03 June 2012 - 04:09 AM

Absolutely worth it. Contact your local sailmaker to meet you at the boat during your next haulout. He can measure and make you a centerboard gasket. You will need a strip of brass or stainless steel quarter oval to attach down each side of the slot. I would recommend going on the 'Flying Scot' website forums and get some info on how they make and install theirs. If you keep the boat in the water you can coat it with bottom paint once installed.



The only thing worse than no gasket is having a gasket HALF attached!
Make sure you secure them firmly if you wont be seeing them for a while.
Leaving a small V shaped gap in the gasket at the back of the case allegedly allows some of the 'static' water in the case to venturi out, reducing the weight the boat has to cart around. Does a Jubilee go fast enough? Is it permissable under class rules?
Do the Jubes still sail out of Brighton?

#4 Fleetwood

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Posted 03 June 2012 - 04:30 AM

Exactly my concern, sailing around with a gasket half attached!
Class rules (written in 1930s) are silent on them.

Jubilees normally are displacement boats, upwind normally about 5kts in a reasonable wind, don't plane easily, need 20+kts, then we do 9+. Good fun!!
Major Melbourne fleet is from Brighton,others at Sorrento and Ballarat. Sydney fleet is on Pittwater.
Any idea on speed difference with/without gaskets?

#5 Major Tom

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Posted 03 June 2012 - 06:13 AM

Are you allowed to put any packing in the case to stop the centreboard slopping around? This would also allow the slot tapes to work more efficiently.



#6 Fleetwood

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Posted 03 June 2012 - 08:05 AM

I did plan to do this too, with delrin or something similar screwed to the board, but others who have tried it find that the board tends to stick, even though its heavy.

#7 knobblyoldjimbo

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Posted 04 June 2012 - 04:26 AM

I have a Careel 18 - sounds similar to yours, big heavy jobbie - centreboard is 85kgs or so.

Slot gaskets are absolutely vital for racing performance.

I swapped mine over a few years ago, the ones that were there (and still effective, if a little mishapen) would have been over 20 years old. Mine are screwed through an aluminium half round. I was going to replace these with batten material but never got around to it.

#8 skiffsailor_aus

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Posted 04 June 2012 - 07:22 AM

Yep, would definitely recommend a gasket. If you have ever sailed a boat with one and then removed it, you can really feel the difference.

The boats here tend to glue theirs on with whatever glue takes your fancy, and then put some kind of tape (can you get 'go fast tape' over there?) on the edges to make it streamlined.

#9 Fleetwood

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Posted 04 June 2012 - 08:26 AM

Thanks, I'll give them a go.
Planning a major haulout / refit this winter so I'll do it then. Probably use SS half-round; don't trust adhesives under water!

#10 knobblyoldjimbo

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Posted 04 June 2012 - 11:42 PM

before you get the half round ss go to your local sailmaker and have a look at his batten material. Now they use what looks like broad 1 1/2 cm wide fibreglass and keep it on a big roll. About $3 per metre. Strong enough to countersink and if you put screws every inch then it should work fine particularly if you're not pulling the boat on and off a trailer.

#11 rantifarian

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Posted 05 June 2012 - 12:30 AM

We used mylar tape for the 420 centreboard tapes, and contact adhesive to glue it down. This website shows the basics of how to install it. Rather than using sail tape, as they recommend, we used to use danger or fragile tape, a strip down each side and then the rounded piece at the front of the case. This may not be suitable for your wet sailed boat, but it could be worth a try. Finding a good quality glue suitable to use underwater would be a nicer solution than putting screws through the skin underwater.

#12 clooless

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Posted 07 June 2012 - 08:43 AM

if you've got a heavy boat already, no harm in using keel band or similar ally strips and screws to keep your gasket in place, lasts a lot, lot longer than contact adhesive, ok not as hydro-dynamic but pain will be outweighed by the gain

#13 clooless

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Posted 07 June 2012 - 08:49 AM

http://www.allenbrot...d_id=116&id=906 or similar?

#14 piggybui

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Posted 07 June 2012 - 11:01 AM

I've a RS400 and I need to replace mine every two years approximately.
There is no cover on it; it just goes straight on and is stuck on simply with Stikafix.
The hardest bit of replacing it is removing the old glue. You will need a sharp chisel.
Once it starts to go gallons of water get into the boat when we're sailing fast or in any bit of a lumpy sea.

#15 Icedtea

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Posted 07 June 2012 - 11:42 AM

They are pretty much up to you in a displacement boat I think, if it was me I'd put them in, but the speed difference mightn't be up to much.
You should try packing the case as had been said before, that will make a big difference to your speed, well relatively speaking!

The only thing to be careful of if doing that is to make sure not to pack it too tightly, as a board that takes longer to go down or will only go down halfway will have you in a world of pain!!

#16 RogerJolly

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Posted 08 June 2012 - 01:18 AM

Gasket and shim the board with something like this.

Posted Image

Jap tape
http://ww2.ibisailing.co.uk/store/advanced_search_result.php?keywords=jap+tape&osCsid=9b037ebea89a4371caa968b68d01240a&x=0&y=0

#17 Fleetwood

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Posted 21 June 2012 - 08:26 AM

Thanks for all the advice; I'll let you know the (eventual) result!




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