TOPIC:

I have decided to re finish my centre board as a winter project. I have two boards to choose from. One that is made up of planks glued edge on edge. I suspect the wood to be spruce. the other board looks to be a solid hardwood possibly mahogany. The hard wood board is heavier. Does any one have a view as to which I should use? I presume that a lighter board would be better or is there an ideal weight.?

I was also thinking of sheathing the board with very thin glass cloth and epoxy. I suspect this will stiffen the board up. Are there any view as to if this is desirable or not?



Regards



Richard Smith

1925

Richard,



Most purpose made wooden foils seem be strip laminated to prevent twisting, so maybe the strip laminated one is the best starting point – Don’t know if there is an ideal known weight on an Alb board, an old NAA guide I have states 8-9 lbs finished - but it may be worth comparing how much your boards weigh with any claims that Milanes/Bloodaxe/Phils Foils make on their foil weight.



The theory behind using glass sheathing seems to be that the glass itself is very strong, but very heavy relative to its size, so using thin layers of glass mat over a light core gives the benefit of the glass strength without adding too much weight.



These can explain it better I can:

OK Website 1

OK Website 2

Wayfarer Website 1

Wayfarer Website 2

As you have two boards you could always test out both of them…maybe even rout out the head on one to be a gybing board.



SteveSteveP2010-01-29 10:37:08

SteveP wrote:

…maybe even rout out the head on one to be a gybing board.

Steve

I wouldnt recommend that as it wouldnt be class legal.



See Rule 7.4

...The top part of the centreboard above the line AD may be of any shape but shall be of uniform thickness

That rules out having a kite section, above the bolt hole. However if you look closely at the graphic on this site it shows how you can have a gybing head within the class:

Phils Foils Alb Centreboard

Although, I’m unsure how effective having only that section of the head routed out would be, even before deciding if it works well enough in an Alb to make it worth while - maybe Richard can experiment?



Steve.SteveP2010-01-29 14:56:15

I had looked at that - I dont think that shaping is to make the board gybe (but I am not sure what it is there for.)






Because the slot width is limited to 30mm, the only possible way to make the board gybe would be to have a very thin board (so it can gybe within the limited c/b slot space). Im not convinced that it would be a good idea.



If my maths serves me correctly a 350mm wide board 20mm thick in a 30mm centreboard slot could only gybe 1.6degrees maximum.



A 10mm board could gybe 3.2 degrees but that is a bit thin for my liking.

Although that graphic may not be the most detailed close up, you can see how it works within the rules - narrower but uniform width above the bolt hole (line A-D in rule 7.4) with the 'kite' cross section below it, this shape terminating at the point the board is in the water flow.



With this you have the potential for the board to gybe - Conveniently 1 to 1.5 degrees is the amount David Ullman talks about for most classes at the end of this article:

National Hornet Article (pdf)



Whether its any good or not in an Alb, and in what conditions, someone may know, but I think that's strayed off topic a bit for Richards winter project.



May be better to discuss which paint/finish is recommended, profile of rear edge to go for etc, but you'll also to look at where the bolt holes are on these two boards vs 1925's current board – worth checking as they may have come from different boats with different bolt hole positions in their centrecases. If it's out by a margin it may affect 1925's 'balance', and worse case scenario you may not be able to fully raise the board!



Steve

Many thanks for all the replies. Some of the links are very useful.



Regards



Richard Smith

1925
Richard Smith2010-01-31 20:04:18