Radial rake measurement
Printed From: Yachts and Yachting Online
Category: Dinghy classes
Forum Name: Technique
Forum Discription: 'How to' section for dinghy questions and answers
URL: http://www.yachtsandyachting.com/forum/forum_posts.asp?TID=12276
Printed Date: 08 Aug 25 at 9:22am
Software Version: Web Wiz Forums 9.665y - http://www.webwizforums.com
Topic: Radial rake measurement
Posted By: piglet
Subject: Radial rake measurement
Date Posted: 16 Jan 16 at 9:56pm
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I realise this is horses for courses and a bit subjective, but,
What's a good rake measurement using a straight radial bottom section? I've got 3425 to where the tape touches the top of the transom, half way round the radius. |
Replies:
Posted By: JimC
Date Posted: 16 Jan 16 at 10:10pm
| Isn't at least 3/4 of the point of having a Laser to not worry about that sort of nonsense? |
Posted By: PeterG
Date Posted: 17 Jan 16 at 9:24am
------------- Peter Ex Cont 707 Ex Laser 189635 DY 59 |
Posted By: rich96
Date Posted: 18 Jan 16 at 6:01am
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I'm sure that someone on the Laser forums will be able to give you an informative answer
The rake issue is not unusual in the Laser |
Posted By: jeffers
Date Posted: 18 Jan 16 at 9:41am
If the build quality was consistent yes. It is much better now than it used to be. We had some boats at Hunts that had masts at very strange angles. ------------- Paul ---------------------- D-Zero GBR 74 |
Posted By: Rupert
Date Posted: 18 Jan 16 at 10:23am
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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? ------------- Firefly 2324, Puffin 229, Minisail 3446 Mirror 70686 |
Posted By: piglet
Date Posted: 18 Jan 16 at 10:39am
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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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Posted By: andymck
Date Posted: 18 Jan 16 at 11:26am
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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 |
Posted By: jeffers
Date Posted: 18 Jan 16 at 11:36am
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 ---------------------- D-Zero GBR 74 |
Posted By: Roger
Date Posted: 18 Jan 16 at 2:11pm
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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.... |
Posted By: jeffers
Date Posted: 18 Jan 16 at 2:18pm
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 ---------------------- D-Zero GBR 74 |
Posted By: laser47
Date Posted: 19 Jan 16 at 11:18am
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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. |
Posted By: piglet
Date Posted: 19 Jan 16 at 1:35pm
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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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Posted By: laser47
Date Posted: 19 Jan 16 at 2:03pm
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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. |
Posted By: bustinben
Date Posted: 20 Jan 16 at 12:36pm
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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!
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