Assuming early Merlins had metal centeboards when did wood/composite plates become the norm? Presumably mid 60's?

Not sure merlins ever had metal boards. All the early boats I've seen have been wood.

Early Merlins - Kate No 1, Iska No 6, Terrapin No 36, Secret Water No 111 (boats built in 1946 and 1947) all have lumps of lead on the end of the centreboard.  Gannet 252 (built in 1951) has a plain wooden board (and a lovely piece of solid mahogany it is too!!) Not sure when the lead was dropped - probably as soon as the Thames was full of lead tips!!   There was an issue in the early weighing of hulls too - they were weighed with the board out.  Boats now are weighed with the board in and are therefore much lighter in the hull.  My board weighs about 7kg!! But if you look at the link at Hampton last year you can see the advantage in a blow!!  I am not aware of any solid metal boards.

Thanks, I just assumed most 50's/early 60's dinghies had metal plates.

As far as I know Merlins never had all metal centreboards and I bow to Garry's knowledge pre 1960 but I do know there was a brief period from about 1967 to Well post 1070 when the boat was weighed with the centrboard in and there was NO maximum centre board weight boats were coming out abot 20 - 30lbs (old money) light and at least two of us, myself and Alan Warren had ballasted centreboards instead of correctors, ours was obeche sheathed in glass anyway, so it was easily done, one needed an uphaul system just like the Metal Centreboard classes.

Could you put some of your correctors from a modern Merlin in the bottom of the board? Of course observing the max board weight...

Can't see why not as it is total weight hull plus foil nowadays.

Quite a few classes did have steel centreplates in the 40s and 50s - Fireflies for certain and I think 12ft Nationals also.

Given that I understand most boards are sheathed or moulded these days (So it should be easy enough to do.)I'd hazard a guess they weigh in less than 8kg unless that is some people are keeping quiet about having max weight boards with the weight in the bottom?

Larks still have metal plates, and don't Finns too?

You sail your boat flat, so putting weight at the end of the board is not going to help.  It will make the boats pitching moment worse which will hinder.

It will help if you sail along on the piss, but if you do that you’re going to be at the back anyway.  So keep the board light and put the lead near the axis the boat pitches around.

It certainly will not help pitching. (The adverse effect over 14' of waterline length against the very much greater effect over about 4' of waterline beam shouls also be noted.) However as we have been taught from Manfred Curry (1936.) onwards, rolling is worse, and in the pursuit of the Holy Grail of sailing flat it's very easy to rock n' roll the boat about especially going to windward as the various videos show all too well, the additional benefit of the weight will help iron this out, as well as helping to right the boat untill (On very rare occasions.) it is absolutely vertical. I have only watched Rogert Gilbert sail a MR once but what was impressive wasn't how flat his boat was (Though it was.) but how smooth it was. Anything that helps this must be a good thing. It's doubtful the funds could be found to really test this, so if it gives you confidence do it if it gives you confidence not to then do that.

In the grand scale of things a heavy board is not going to affect pitching that much. The rig weight will have a much greater effect.

Interestingly Winder boards are not carbon they are glass.

Squirrel (235) has solid mahogany wood board and my first merlin Calinda (169) also had solid wood board in both cases with tip protected by thin brass band. Both boats built by Jack.

252's board has the protective strip of brass on the tip

Jack Chippendale or Jack Holt?

Book says Holt

Early Merlins all had weighted wooden centreplates - no bolts but rollers that ran up and down along the top of the plate casing. Absolute works of art - some had lead bottoms -others had wonderful brass weights let into the mahogany boards. 

Conventional wisdom holds that weighted boards don't help to hold he boat upright. By far the worst problem with these boards is trying to get the balance right and over come the inconsistencies. Doubtless a wondrous idea - just too difficult (for me). Jamie

Ballasted Centreboards.
The Ballasted centreboard fell out of favour for the basic reason that whilst it was efficacious it was not included in the weight of the hull and was thus immobile weight, the early shenanigans of disguising the fact that a centreboard was not ballasted the pantomime of carrying it as if it was ballasted have been well described in various books and articles, by Uffa Fox, Peter Scott, Keith Shackleton and Beecher Moore. Uffa Fox in particular to sell the idea to his customers, suggested they did not help righting, they certainly did but the handicap of the extra weight did not! This was all before and just after the 2nd World War and it is likely that the early Merlin Rockets progress from ballasted to unballasted were influenced by the International 14 experience especially as there was a 14 fleet at Ranelagh and Tamesis both early bastions of the Merlin Rocket Class.
I was convinced of the efficacy of ballasted boards as a benefit to stability when in 1965 I together with Brian Southcott sailed for Tamesis in a Team Race against the International Canoe Club (Neighbours to Tamesis.) in sailing canoes, in the first race Brian drew an early canoe with a load of lead on the bottom of its centreboard and I a modern one without. Brian sailed serenely into the distance and I didn’t even start I capsized countless times. For the 2nd race boats were swapped and I sailed into the distance and it was Brians’ turn to swim!
Thus when Duncan Henderson (Who was responsible.) put through the rule change that permitted the board to be weighed with the boat, (To simplify check weighing at Championships.) with no maximum weight to the board, I, with others noted it, and I ensured that my next Merlin Rocket was built well under weight and made up the weight with a ballasted board which was made from laminated obeche with a lead bottom and sheathed in GRP that we vacuum bagged to ensure good bonding. It weighed 40lbs.(18kg or thereabouts.)
I thought it made a difference in ironing out the movements of the boat and when up or part way up moved the weight back in the boat (Downwind.) too. On balance it puts compulsory weight in the right place the current 8kg max weight on a board wouldn't allow a lot of lead, but every little helps.