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Radial rake measurement
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bustinben View Drop Down
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Posts: 288 		Post Options Post Options   Quote bustinben Quote  Post ReplyReply Direct Link To This Post Topic: Radial rake measurement
    Posted: 20 Jan 16 at 12:36pm
Take it from someone who is currently active in the class and has had 3 brand new ones - there are still big variations.

For most sailors, it's not going to matter what the measurement is, you just want to make sure you don't have an outlier.  If you're not as quick as other people it's much more likely to be your technique than anything else!


Edited by bustinben - 20 Jan 16 at 12:40pm
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laser47 View Drop Down
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Posts: 349 		Post Options Post Options   Quote laser47 Quote  Post ReplyReply Direct Link To This Post Posted: 19 Jan 16 at 2:03pm
From the top/back of the mast to the middle of the round of the transom (just above the rudder fittings).

There's pictures and instructions to measure everything in the older versions of the Laser Campaign Manual, I'm not sure about the newer version because no-one really measures anymore: the XD makes it less of an issue and they seem to have clamped down on the tolerances since the early 2000s.
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piglet View Drop Down
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Posts: 514 		Post Options Post Options   Quote piglet Quote  Post ReplyReply Direct Link To This Post Posted: 19 Jan 16 at 1:35pm
Thanks 47.
148"-152" is a substantial variation, as you said I'll have to borrow a std section.
Exactly where on the transom?
Thanks again.
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laser47 View Drop Down
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Posts: 349 		Post Options Post Options   Quote laser47 Quote  Post ReplyReply Direct Link To This Post Posted: 19 Jan 16 at 11:18am
All the rake guidelines I know of are based on the standard mast, you'd be better borrowing a full rig and measuring top to transom on that.

For the standard rig I've always been told they're *supposed* to be about 382.27/383.54cm or 150.5/151in from the top of the mast. A bit of forward rake (Up to 386cm/152in) is better because it's quick off the wind and gives you better leech tension upwind. If the measurement is less than 376 cm/148in you've got an issue with the bottom of your mast step and the boat's a dud.
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jeffers View Drop Down
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Posts: 3048 		Post Options Post Options   Quote jeffers Quote  Post ReplyReply Direct Link To This Post Posted: 18 Jan 16 at 2:18pm
Originally posted by Roger


I of course just took the hull they gave me....


As did I when I bought a  new Laser (180,000 vintage). A friend of mine however didn't as the hull had visible stress cracks all over it so he refused it. After several hours or discussion and him demanding a refund they eventually replaced the hull with a new one (and had to change the numbers etc.. that they had packed for him).
Paul
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Roger View Drop Down
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Posts: 524 		Post Options Post Options   Quote Roger Quote  Post ReplyReply Direct Link To This Post Posted: 18 Jan 16 at 2:11pm
Back in the day..... 1980's I went to pick up a new Laser from Banbury.
There that day were a couple of hot shot, top of the fleet guys, they spent hours weighing hulls and checking the rake by putting their own chosen bottom section in the pot of what seemed like dozens of hulls, they very carefully chose the ones they wanted, can't remember how they checked the rake, but they did say there was big variation. I remember my boat was a 128*** number, which kind of dates the time.

I of course just took the hull they gave me....
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Posts: 3048 		Post Options Post Options   Quote jeffers Quote  Post ReplyReply Direct Link To This Post Posted: 18 Jan 16 at 11:36am
Originally posted by andymck

The issue was not the pot. They are all the same. The issue was the deck bond. If you look at any boat that has the deck bonded in this way there will be a varying thickness all round the boat. The pot angle was set by the mold, but if there was a slight excess of bonding agent at the bow compared to the stern then there was a significant affect on the overall mast rake. This also means the measurement for rake needs to be taken to the bottom of the hull as the measurement to the deck should be fairly reproducible. I suspect no one noticed until it became an Olympic class.
Now they are aware what the issue is, it can be looked at in the process. I suspect it took a lot of working out what the issue was.

That and there is a bit of tolerance at the bottom of the pot that allows it is sit off centre (that is usually full of bonding paste) if it has not been put together perfectly.
Paul
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andymck View Drop Down
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Posts: 397 		Post Options Post Options   Quote andymck Quote  Post ReplyReply Direct Link To This Post Posted: 18 Jan 16 at 11:26am
The issue was not the pot. They are all the same. The issue was the deck bond. If you look at any boat that has the deck bonded in this way there will be a varying thickness all round the boat. The pot angle was set by the mold, but if there was a slight excess of bonding agent at the bow compared to the stern then there was a significant affect on the overall mast rake. This also means the measurement for rake needs to be taken to the bottom of the hull as the measurement to the deck should be fairly reproducible. I suspect no one noticed until it became an Olympic class.
Now they are aware what the issue is, it can be looked at in the process. I suspect it took a lot of working out what the issue was.
Andy Mck
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piglet View Drop Down
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Posts: 514 		Post Options Post Options   Quote piglet Quote  Post ReplyReply Direct Link To This Post Posted: 18 Jan 16 at 10:39am
I have had 2 very different and very good Laser sailors tell me that they have both had boats with a slightly forward/upright pot, and that under certain conditions the boats seem to be quick if you can get it right.
I don't suppose for one minute I would be able to tell the difference but the reason for asking was that I was looking at buying a 'medium age' (16# ###) boat and I wanted to check it wasn't a friday afternoon boat.
 
I think most people would agree that LP have improved QA in recent years.
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Posts: 8956 		Post Options Post Options   Quote Rupert Quote  Post ReplyReply Direct Link To This Post Posted: 18 Jan 16 at 10:23am
Looking at the way the boat is sailed, I assume the more upright the mast is, the more kicker you can Wang on before the boom hits the deck?
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