Mast Rake, Anyone Measuring?

T

TheBoathouse

New Member
We have been Laser Dealers since 1991 and early on all the "hot" sailors would come in and want to weigh new boats and measure mast rake to choose their hull. For the last, I don't know 5 to 6 years, I haven't had anyone request this. However the other day I had someone ask me to measure all the mast rakes of the in stock boats but I told them the tolerences are so small now that no one is measuring mast rake anymore. Has anyone been measuring mast rakes in the last few years? Any comments? Scott Fox
The Boathouse
 
in days of old mast rake was a huge factor, with great differences between even two boats built in succession.

it is my understanding sunfish/laser in the early 90s created a device that accurately set mast rake within a very tight tolerance. in any case, mast rake, like so many items that used to be problems, is rarely an issue in a modern laser.

i'd wager the person scott is dealing with is an "old-school" laser sailor who doesn't know the current building standard.

marc jacobi

p.s. there *was* some controversy at the 2000 us olympic trials when a competitor claimed his mast rake and also side-to-side measurement was off. i don't recall exactly what the result was of it, however.
 
Just out of curiosity, for those of us with older boats (ex. '92), what is the desirable range of mast rake?

Cheers,

Geoff S.
 
TheBoathouse said:
....Has anyone been measuring mast rakes in the last few years? Any comments?...
The Boathouse
Click to expand...

Dear Mr. Fox

Of course the mast rake is important, also in our days. If the Laser is sailed “block to block”, only the mast rake “can” control the twist of the (upper) leech (triangle) of the Lasersail.
We, the readers at TLF, learned from several TLF-threads here, that there still A R E different qualities of the “1-design”-aluminium-Laser-mast, produced at several continents on that potato, we all live on.

Personally, I´m a lucky guy, because I´m a non-racer - I can take everything for a Lasermast, even a cutted flag-mast (if suitable…. :)). But if I were a racer, I would be suspicious and measure and proof everything, if I would have to buy something new for my Laser –also in our days or in future.

I know from German-semi-pro-racers here, that they buy their Lasermasts in Australia (because they say, the stiffest Lasermasts of all today are built down under)

Mast rake and the mast-bending-possibility are brothers. Remember the TLF-thread “older mast vs. newer mast” (thread 1568)

Cheers

LooserLu
GER46438
DLAS-member
 
in Ben ainslies laser campaign manual
he says that:

measure from the top of the bottom section to the middel of the transom - 148 inches is raked back, 152 inches is raked forward, if iin doubt forward is better because its quick down wind and you get good leech tension upwind,
(this is for a full rig bottom section. i think if you tried it with the radial or 4.7 then this would be wrong as they are shorter.)

then you can measure from the top of the bottom section to the side of the deck each side so you get to see if there is any vertical bend

hope this helps.

Sailor Jon
radial 144679 !UK yay!
 
Does it matter?.. I think it does.. in a class where you fight for inches on the race course.. everything matters.. I measure and weight everything.. I mostly found that hull fairness was noticeable different from hull to hull. Some hulls had indents or bumps where the aft end of the cockpit is located. Nothing big.. just small differences. Mast Rake is still an important measurement. Why leave things to chance.. Old school or not..I call it diligence.
 
So Peter, what sort of variance did you find in the hull weights and mast rakes when you bought your boat ?
 
Most of you are missing my point. Yes I agree mast rake matters especially on older boats were there were a lot of variances. My question is specific to newer boats (say 2000 and up). Is anyone measuring mast rake on newer boats and is anyone finding critical differences?
 
@Mr.Fox:
Sorry no, I think such a boat I´ll get fewest in about 20 years [My good running Laser I now own is from 1977] ;)
Cheers
LooserLu
 
49208 said:
So Peter, what sort of variance did you find in the hull weights and mast rakes when you bought your boat ?
Click to expand...
I've done this twice... First time (my current boat).. amazing differences in weight and mast rake.. 1/2"-3/4" measuring just from the top of the lower section.. weight differences +/- 5 or 6 lbs. (scale error could of accounted for some of that) Second time.. all boats had very similar rakes and weight.. bottom fairness differed.. I guess if depends on the batch you look it.. My target measurements were taken off a proven rocketship boat and mast combination that one master wish he never sold... Bottomline.. more then getting a fast one.. you want to cut your chances down of getting a slug.. and please no one try to tell me there are no new slow boats out there.. ask Raab.
 
Got this in a mailshot from Steve Cockerill at the weekend, hope he doesn't mind it being quoted here...

QUOTE
The conclusion to mast rake tests performed was that 3.082 is the current average. My boat at present is 3.0825 and that 3.083 would make the boat slightly better on flat water upwind and downwind. Rakes of 3.79 and below can work well on the sea - but they can be found wanting for height on lakes and in marginal hiking conditions. To measure the rake, use a standard bottom mast - attach the tape measure to the top of the bottom mast and measure to the point where the tape touches the back of the boat in the middle. ......send me your results and feelings to [email protected]
P.S. - check out how upright your mast is too - measure post to starboard at the same time. I got 11th in Spa Regatta once in a laser that had a 5cm difference from port to starboard!
END QUOTE
 
At a recent regatta, we were shore bound waiting for wind to die down and some of the more bored sailors started measuring rake on a number of different boats of very different ages 1994-2004. One of the boats had just been picked up from the dealer that day. Mast rake was very close with little more than an inch of variation from bottom section pushed forward to pushed aft. This was incouraging. However there was variation in side to side measurements.

I was skeptical of this because if you start to think about it, it seems very difficult to standardize this measurement. Remember first of all, that the mast is round and in a round tube, therefore it would be very hard to know whether you were holding two masts in the same exact position. Furthermore, where do you measure to? the deck of a laser or any other boat runs on a continuous gradient curve. Finding a location that is the same within tight tolerances will be very difficult if you ask me. It seems like a framing square would have to be used.

That said, if there is variation among masts for side-to-side measured from the top of the bottom section, this variation will be heavily compounded from the top of the upper section and may actually be a serious point of contention.

It will take some seriously careful measurement to find this out. Maybe the class measurer has already done this and can shed some light into the situation. Do we have a class measurer still? Who are they?
 
MScott said:
... It will take some seriously careful measurement to find this out. Maybe the class measurer has already done this and can shed some light into the situation. Do we have a class measurer still? Who are they?...
Click to expand...
Scott,
of course there is ""a" measurer": His name is Jean-Luc Michon and he is the ILCA-World-Council Vice-President & European Vice Chairman and Chief Measurer for the Laser round this globe. DrLaser,Shevy, already mentioned his name here at TLF... ;)
Where "they" are? I don´t know, maybe with the pro´s.

What´s to do? My answer: Stastistics! No one loves this, but it´s useful. My advice: Make a "Testing in Hypothesis" ("zero/0"-Hypothesis against "alternative Hypothesis" it is called in the mathematics {Sorry for my English for "runaways", please}, I remember from my studies at universitiy. If I would have more time, I would explain, but I have none in the moment, sorry. Maybe someone other, please).

I think also, nearly all at the Laser is measured. I know there is an exact manual for building a Laser, where all stands in. This Manual/Laser-"bible" is only known to a few persons. All the original-Laser-builder-Inc´s, the high-ILCA-officers (I think), the ISAF, Bruce Kirby, Ian Bruce, Hans Fogh.

Like in the thread "older mast vs. newer mast", we need more real numbers here. The more numbers we have, the more precise we can get to answer that problems with mast-rake or mast-bending. It´s up to you. If you need the numbers from my old ´77-PSE-Laser (Mr. Fox :) ), I´ll go out to the winter-home of my Laser and get them for you, of course.
Ciao
LooserLu
 
HI:
I have a one year old boat 178529. It is so slow. I went from the top of the fleet of 15 boats at frostbite to DFL. The last boat was a 156XXX series and was fast I should have never sold it .This new boat is so slow it's unbelievable. I'm going to start measuring boats of the "fast' guys. I'm going to measure foward and aft mast rake and side to side mast sag. I'm also going to measure weights. I sail etchells in the summer and we move the mast alot. 4 inches at the deck and almost three feet at the top of the rig. Way back in at the top in heavy air UW, and way foward in light air DW. Side sag at 3/4 inch at the spreaders. So I'm really tuned into the whole mast thing. anybody else have any suggs. on the slow boat?
Bill Fox, Chicago, 178529 (Slow!!)
 
peterbye said:
Got this in a mailshot from Steve Cockerill at the weekend, hope he doesn't mind it being quoted here...

QUOTE
The conclusion to mast rake tests performed was that 3.082 is the current average. My boat at present is 3.0825 and that 3.083 would make the boat slightly better on flat water upwind and downwind. Rakes of 3.79 and below can work well on the sea - but they can be found wanting for height on lakes and in marginal hiking conditions. To measure the rake, use a standard bottom mast - attach the tape measure to the top of the bottom mast and measure to the point where the tape touches the back of the boat in the middle. ......send me your results and feelings to [email protected]
P.S. - check out how upright your mast is too - measure post to starboard at the same time. I got 11th in Spa Regatta once in a laser that had a 5cm difference from port to starboard!
END QUOTE
Click to expand...

HI:
I have a one year old boat 178529. It is so slow. I went from the top of the fleet of 15 boats at frostbite to DFL. The last boat was a 156XXX series and was fast I should have never sold it .This new boat is so slow it's unbelievable. I'm going to start measuring boats of the "fast' guys. I'm going to measure foward and aft mast rake and side to side mast sag. I'm also going to measure weights. I sail etchells in the summer and we move the mast alot. 4 inches at the deck and almost three feet at the top of the rig. Way back in at the top in heavy air UW, and way foward in light air DW. Side sag at 3/4 inch at the spreaders. So I'm really tuned into the whole mast thing. anybody else have any suggs. on the slow boat?
Bill Fox, Chicago, 178529 (Slow!!)
 
Etchells615 said:
HI:
...anybody else have any suggs. on the slow boat?
Bill Fox...
Click to expand...
Did you tried another (tested fast-)sail? Maybe the new sail is not complete "break in" (see TLF-Thread No. 1372 "New Sails" at TLF-sailing-discussion-area).
Good luck
LooserLu
 
Etchells615 said:
HI:
I have a one year old boat 178529. It is so slow. I went from the top of the fleet of 15 boats at frostbite to DFL. The last boat was a 156XXX series and was fast I should have never sold it .This new boat is so slow it's unbelievable. I'm going to start measuring boats of the "fast' guys. I'm going to measure foward and aft mast rake and side to side mast sag. I'm also going to measure weights. I sail etchells in the summer and we move the mast alot. 4 inches at the deck and almost three feet at the top of the rig. Way back in at the top in heavy air UW, and way foward in light air DW. Side sag at 3/4 inch at the spreaders. So I'm really tuned into the whole mast thing. anybody else have any suggs. on the slow boat?
Bill Fox, Chicago, 178529 (Slow!!)
Click to expand...
Hi Bill,

You've already got some mast rake numbers posted here that should help you, in addition to the numbers you get from your boat and others in your fleet.

A +5 or even +10 lb weight change is not going to make that big a diff unless it's all in the bow or stern and completely changes the center of gyration, and even then you would not notice it in flat water as much as waves/chop

Other areas to look at in addition the mast rake and weight are:
Sail as someone else suggested (try a different sail)
Rudder/Daggerboard alignment (make sure they are vertical and in the center of the hull
Rudder/Daggerboard shape - no obvious defects/symmetrical
Hull fairness - again no obvious defects
Mast stiffness - (try a different mast)

Good luck
 
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