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Singlehander Layout Ideas

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Rupert View Drop Down
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Post Options Post Options   Quote Rupert Quote  Post ReplyReply Direct Link To This Post Topic: Singlehander Layout Ideas
    Posted: 11 Jun 16 at 7:03pm
It was the Unit which had the tractor seat, briefly.
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Chris 249 View Drop Down
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Post Options Post Options   Quote Chris 249 Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jun 16 at 10:51pm
I thought it was the Jack Knights/Binks boat? I have the pics and plans before it was built and at the second (or third?) trials.

I'll check; I was going to scan the plans and pics to put them up up my blog soon anyway.


Edited by Chris 249 - 11 Jun 16 at 10:52pm
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Dougaldog View Drop Down
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Post Options Post Options   Quote Dougaldog Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jun 16 at 11:15pm
Well, you are both right.

Certainly the Binks/Knight boat had a tractor seat, but it was mounted on something more like a gun mount.

Rupert IS right...in part. At the second set of Trials (La Baule) David Thomas was there with Unit, complete with a sliding seat. However, Unit 2/7 was also there in the hands of Richard Creagh-Osbourne and this (it was the second boat but had sail number 7) had a tractor seat mounted on what can best be described as a giant pair of scissors!

Back to the original post from Jim C..... some of the boats in the Trials had extensions very similar to  those suggested by Jim as ways of 'extending the crew weight beyond the gunwale'. Probably the most successful of these was a system whereby the extensions were mounted on a pivot point on the side tank. When tacking, the helm just had to push the extension forward and outboard and it was there to use. It had a retrieval line that could be used to pull the leeward seat back from the windward side.

However, none of these systems were as successful as a simple sliding seat.

BUT...what is even more interesting, is the details from the Autumn 1952 'semi-official' Trials held at Itchenor when the FD was put up against the Osprey, 14, Merlin Rocket and modified 14 (with self draining cockpit and trapeze.)

One of the outputs of this was a technical statement comparing the use of a trapeze v sliding seat! Some of it was...well, best to say we know better now (one of the statements made was that the sliding seat increased compression loadings in the mast more that the trapeze!!)

Now this was a full 13 years before the first single hander trials..... it just goes to show the ambivalent attitudes that existed towards the issue of extending the crew weight outboard.

D
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Dougaldog View Drop Down
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Post Options Post Options   Quote Dougaldog Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jun 16 at 11:23pm
And one further point...the original plan for the Unit had an interesting and innovative solution for getting the weight outboard.

The first plan had a pole on each side of the hull, angled out from the centreline and extended outboard.

The idea was that the helm wore a harness not dissimilar to a trapeze harness, which then connected to the underside of the pole.

It looked scary and quite simply...it didn't work and was quickly replaced by a sliding seat

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JimC View Drop Down
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Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 12 Jun 16 at 12:10am
Originally posted by Dougaldog

However, none of these systems were as successful as a simple sliding seat.

Maybe it depends how you measure success. There are, as well as I can judge, rather more active racing boats in the world using the simple moderate style of folding winglet than there are boats using sliding seats. They just aren't in the UK.

The sliding seat has no peer when it comes to providing maximum righting moment, and the International Canoe has no peer when it comes to providing upwind performance in a single handed boat.

But age does weary, and after over 40 years sailing boats that were at the ragged edge I'm forced to consider something more moderate, and the well established folding winglet looks like a useful thing to consider, potentially bringing a useful increase in upwind power with a minimum of weight and drag
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RS400atC View Drop Down
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Post Options Post Options   Quote RS400atC Quote  Post ReplyReply Direct Link To This Post Posted: 12 Jun 16 at 10:28am
Originally posted by Dougaldog

......
One of the outputs of this was a technical statement comparing the use of a trapeze v sliding seat! Some of it was...well, best to say we know better now (one of the statements made was that the sliding seat increased compression loadings in the mast more that the trapeze!!).......
D


You don't believe this?
The trapeze effectively acts as a shroud at a wider angle.

The force on the trapeze wire is 1x crew weight.
The tension in the shroud is crew weight x leverage of plank length from centreline divided by shroud distance from centreline.

Compression in the mast is sum of shroud tensions cos the angles they meet the mast at etc.


It's a bit more complicated than that, due to rig pre-load etc etc.

But the simplest case, an RS600 windward shroud can go slack.
And a B14 needs thicker shrouds than a trapeze boat.
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Do Different View Drop Down
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Post Options Post Options   Quote Do Different Quote  Post ReplyReply Direct Link To This Post Posted: 12 Jun 16 at 10:48am
Thank You RS   Smile

Forever hear people saying oh no mustn't put a trapeze on it, the mast will fold under the compression  Cry

I never could see the logic in it, always thought wide racks sending the stress through a narrow shroud base would create higher loadings. For certain though there's lots going on...................
  
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Daniel Holman View Drop Down
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Post Options Post Options   Quote Daniel Holman Quote  Post ReplyReply Direct Link To This Post Posted: 12 Jun 16 at 2:48pm
Equally compression is a function of righting moment as well as the angles that the shrouds subtend.
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JimC View Drop Down
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Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 12 Jun 16 at 7:15pm
Originally posted by RS400atC

It's a bit more complicated than that, due to rig pre-load etc etc.

Its a lot more complicated than that...

For example, because the trapeze unloads the shrouds, most trapeze boats run a great deal of static rig tension in order to keep the spreaders working. A major point of the sometimes decried diamonds on the RS600 is that the mast support is independent of shroud tension, so there is no need to run very high rig tension to support the mast with that rig setup. But in most cases a boat with trapezes requires higher static tension than boats with wings or sliding seats.

Edited by JimC - 12 Jun 16 at 7:16pm
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Rupert View Drop Down
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Post Options Post Options   Quote Rupert Quote  Post ReplyReply Direct Link To This Post Posted: 12 Jun 16 at 7:42pm
Anyone else remember the Delta? Trap singlehander with unstayed mast. Saw it at the Dinghy show long ago, have seen the odd one for sale, but I suspect it was a boat that would have worked if kept more traditional, like the small Contender some seem to want!
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