Firefly centreplate pulley arrangement

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Garry R
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Location: Chapel Allerton Somerset

Firefly centreplate pulley arrangement

Post by Garry R » Wed Jan 30, 2008 10:51 am

Thinking ahead - when I got Vivette the centreplate had been removed but so also had the various control lines for raising and lowering the beast and wondered if anyone had a picture of this arrangement they could email me to show how it comes together. There are two cleats under the thwart - one on each side - are they players in this? My email address is gjr@rowett.ac.uk for posting. Thanks in advance.

Similarly there was some sort of centre mainsheet arrangement which I do see on the modern Fireflies but assume (correctly?) that this is not appropriate for a 1951 model. What was the advantage of going centre main?

The hull is about 70% cleaned up now - I discovered another lovely chunk of fibreglass and filler which I routed out and replaced by lamination. Still some considerable scraping to be done to get rid of the semi-circular scoring but a cabinet scraper is doing a great but slow job. By the weekend I hope to have her turned over and get the deck off ready for timber arrival on Monday according to Robbins. Mid March scheduled for completion all being well.

Rupert
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Post by Rupert » Wed Jan 30, 2008 11:04 am

Hi Garry, if you have an aluminium centreplate, you just fix 2 blocks on the hog under the front bag, then take a line from a cleat on one side of the boat , round the block, up past one side of the mast, round a block on the top of the centreplate, down again past the other side of the mast, round the 2nd block on the hog and back to a cleat on the other side. Where the cleats go on a narrow side decked boat is up to you. They often go on the back edge of the foredeck. I have a slightly different arrangement in that I have a cleat mounted on the case bracing piece, and just start the rope on the hog under the front bag, round the block on the centreplate, down to the block on the hog and back to the cleat, which is near enough to the centreline to be used from both sides.
If you had a steel plate, you'd need to blocks on the plate and 3 on the hog to be able to lift it...
As for centre main sheets, a few people who are more used to them use them, but they are no faster, cut the boat in half and make sailing single handed a pain, as it is more difficult to hold tiller and main sheet in one hand. Very un 1951, too, but then so are the decks!
Rupert

Bill Sylvester
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Post by Bill Sylvester » Wed Jan 30, 2008 11:13 am

There are a couple of other reasons why people go for a centre main. Although you lose a certain amount of leverage, you need to handle less sheet to adjust the angle of the main. In addition, when the boom is eased a little, a centre main will still be pulling downwards, albeit at an angle, when the traditional main can only pull sideways.

I have always sailed with a stern main and took out the Merlin hoop after a single season.

Pat
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Post by Pat » Thu Jan 31, 2008 3:00 pm

Sounds identical to the centreboard arrangement on old Larks so I'll se if I've a photo. Thinking about it I may even change our modern Lark to that as the current string always seems to be inaccessible in a hurry.
(Half Cut and What a Lark Removals Ltd)

Michael Brigg
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Post by Michael Brigg » Sat Feb 02, 2008 12:29 am

[quote]"There are a couple of other reasons why people go for a centre main. Although you lose a certain amount of leverage, you need to handle less sheet to adjust the angle of the main. In addition, when the boom is eased a little, a centre main will still be pulling downwards, albeit at an angle, when the traditional main can only pull sideways."

I think Bill is sailing here with an illegal mainsheet arrangement: I always understood that if a centre main was fitted in the firefly it was necessary to keep an attatchment to the transom horse.The sheet should be attached firstly to a single pulley at the end of the boom and from there through a single pulley the transom traveller, back through the pulley on the boom end then forwards along the boom to a single pulley about 100cms from the end of the boom and thence down to a single (often ratchet) pulley on the stern end of the centreplate case. This arrangement is legal because it does not provide any advantage with regard to leverage or allow any increase in ability to "pump" the main during a roll tack or gybe and also ensures that there is no difference in the movement of the traveller at the transom whose scope is specified in the class rules.

Wether you have a centre=mounted or transom mounted main is determined by your preference for tacking/gybing in the foreward facing or backward facing position which is itself partly determined by how fat the crew/helm is.

I believe it is legal to increase the leverage from the conventional 2:1 up to 3:1 if say you are a junior and find the main a little to much to handle but you may not reduce it.

If you have a centre main it is common practice to have some sort of support for the sheet as it passes forward in order to pevent death by hanging/garrotting during gybes where the slack sheet hangs down from the boom to catch the unwary!

Centre mainsheets were introduced @ the 3000 mark ie well after Vivettes time.

Im sure Vivette's original centreplate will have been Heavy but to be honest it's not the weight that makes lifting difficult. It's the friction inside the case which is increased by lee bow on the upwind leg and this is where most lifts need to be undertaken during short tacking ub tide on a muddy river or estuary. What I'm saying is there's no need to have different arrangements for a heavy or light plate.

The mark1 had a tubular brass "v" cleat on the inner aspect of the side deck just forward of the shrouds. the rope went from here to a pulley fixed to a "Y" shaped fitting forward of the step up to a pulley on the plate and back to the other arm of the "Y" fitting and up to the "V" cleat on the opposite side.

I do not know of a better arrangement. the rope between the Cleat antd the forward pulle is easily grabbed by crew or helm when unexpected groundigs occur and can be very quickly fixed/released. Having no moving parts it has no parts that can fail (unless you can't tie a figure of eight knot, and "does the simple things well" which the English football team might do well to consider!

Becks for a century!?

Regards
Michael Brigg

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Ed
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Post by Ed » Sat Feb 02, 2008 9:28 am

Reckon Michael is exactly right re the plate hoist.

Personally, although the steel plate would be more original, I think that the ali plate is much easier to live with and along with galvinised rigging and cotton sheets, I would change if at all possible.

In the back of my head I think.....just think I might have a couple of those cleats....but would have to check.

But it also brings up the old thorny question....to what 'age' are you restoring her? To original state? with woodtop revolving mast and two-part forestay.....spoon rudder and steel plate? or to modernish with Proctor C, ali plate, dagger rudder. Either way the CVRDA handicap should reflect the changes that are made.

cheers

eib
Ed Bremner
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Rupert
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Post by Rupert » Sat Feb 02, 2008 9:01 pm

It has always been the advantage of the Mk1 deck, the siting of the plate hoist cleats, (apart from the fact that they are exactly where the crew sits) and the tube cleats work well there. However, on the narrow decks the angles are all wrong for them to work properly.
Rupert

jonathan
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Post by jonathan » Sat Feb 02, 2008 10:35 pm

Hi garry.

My UK N12 is I suppose the clinker precursor to the Firefly and for her steel plate there is still the original system which is dual control with a single block at the plate and tube cleats on the deck. Its is a heavy system and any little person crewing has a hard job lifting the plate.

Therefore i would suggest you improve the ssytem though that will mean more rope floating round the bottom of the boat or trailing over the edge.

Ian Malcolm
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Re: Firefly centreplate pulley arrangement

Post by Ian Malcolm » Tue Feb 05, 2008 12:26 am

I use a Holt Allen drum winch intended for tensioning a kicking strap to control the 1/4" galvanised centerplate on my Albacore. It is attached to the hog just in front of the case. The drum is loaded with 4mm line and the shaft is loaded with 3mm Marlow Excel D12 dyneema instead of wire. The white stuff on the top front edge of the case is a sheet of PTFE so the plate uphaul pennant runs smoothly. The uphaul control line leads aft to a cam cleat a little behind the thwart where either helm or crew can control it. The thicker white line is a downhaul for cleating the plate *down* in nasty conditions. It and its Nylon V cleat are chosen to let the downhaul slip on any impact.
There is plenty of mechanical advantage on the uphaul, something like 10:1 without too much rope everywhere.
cb1.jpg
Centreboard Tackle 1
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cb2.jpg
Centreboard Tackle 2
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cb3.jpg
Centreboard Tackle 3
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The setup works nicely on any point of sail except hard on the wind and hiking.

Ok, so its not original, but if one loaded the winch with wire, used 3 strand 1/2" line for the control line and replaced the teflon sheed with a nicely polished bit of stainless sheet or possibly a small sheave, it would pass for period. You'll have to scour the jumbles for the drum winch, They were discontinued a good few years back

The centreboard has two ply cheekpieces at the top so my case doesn't get chewed up - best compromise I could come up with between being strictly class legal and *NOT* breaking my boat.
Ian Malcolm. London, ENGLAND. (FORUM REPLY PREFERRED)
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[at]=@, [dash]=- & [dot]=. *Warning* HTML & >32K emails --> NUL:
'Stingo' Albacore #1554 - 15' Early 60's, Uffa Fox designed,
All varnished hot moulded wooden racing dinghy.

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