Forums > Land Yacht Sailing Construction

Class Five Design

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Created by blake52 > 9 months ago, 3 Dec 2010
blake52
123 posts
16 Dec 2010 12:45AM
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I have heard the wheels are made by or for Seagull. Spun Aluminum. I'll check; I know someone who bought a set at the worlds.
I just emailed my friend and posted the question on the FISLY forum..."News at 11" as they say.

grlynch
QLD, 208 posts
16 Dec 2010 8:12AM
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A little bit off topic, however What sort of tolerances are required for having wheels made?
I have worked with metal spinning quite a lot and I would have thought the process would not have been accurate enough. Usually with hand spinning on a timber pattern I would expect +/- 0.5 to 1.0mm (I'm not sure even CNC spinning would be good enough)

blake52
123 posts
16 Dec 2010 6:50AM
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Being 1 mm off would create a wobble, I would think. but the centers are welded in and I'm not sure how they join the rim, maybe the truing occurs when the parts are assembled.

Hiko
1229 posts
16 Dec 2010 6:59AM
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I must be a roughie 1mm wobble on my 26inch f/glass rims I would think was good
Imac here in NZ used to make aluminium class 5 wheels when they were 19inch
I think I dont know if they still make any Grlynch if you can make them you might be on to a winner!

blake52
123 posts
16 Dec 2010 7:42AM
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I know I couldn't build fiberglass wheels that true...I might be metric challenged; 1mm is not really much...my brain was thinking that was 1/8 in which is closer to 3mm which you could see and feel on a bike wheel...

Clemco
430 posts
16 Dec 2010 10:05AM
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Ian MacLachlan (Imac Engineering) in Palmerston North NZ made the 19" and 26" aluminum wheels. Not sure if he made them for the French but I know he sent quite a few over to the UK. Unfortunately Ian has wound up his engineering business and is now teaching engineering at a polytech in New Plymouth NZ. Unfortunate for us but good news for his students as Ian is an exceptionally clever engineer. The disks were spun up against a solid steel mould. The rim was rolled out of flat sheet and somehow folded over the edge of the disks. The hubs were welded in last. I dont know how he did it but they were all damn near perfect. One of his YOTTs is up for sale now. (see pic below). Not sure if it comes with 19" or the 26" wheels as in the photo. If anyone is interested send me a PM and I will give you Ian's email address. I dont know the price.

aus230
WA, 1659 posts
16 Dec 2010 8:34PM
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I checked my fiberglass wheels today, They are just under 1/8" out of round, I don't notice it at all when I am sailing. The wheels have held together well and have done some hard racing, They have cost me around $50 to $60 each to make, they weigh 3.5kg with the Tyre. I am going to make a couple of more soon so I will take pics and notes and post on here as I go. Have improved on the first ones I made. I think I have overcome the problems I had with the first type pair
www.seabreeze.com.au/forums/Land-Yacht-Sailing/Construction/Building-new-class-5/
Cheers
aus230

aus230
WA, 1659 posts
16 Dec 2010 8:35PM
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I checked my fiberglass wheels today, They are just under 1/8" out of round, I don't notice it at all when I am sailing. The wheels have held together well and have done some hard racing, They have cost me around $50 to $60 each to make, they weigh 3.5kg with the Tyre. I am going to make a couple more soon so I will take pics and notes and post on here as I go. Have improved on the first ones I made. I think I have overcome the problems I had with the first pair
www.seabreeze.com.au/forums/Land-Yacht-Sailing/Construction/Building-new-class-5/
Cheers
aus230

blake52
123 posts
17 Dec 2010 1:33AM
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Yes I saw the posts about building those...good work. I wonder if a little carbon thrown into the mix would be a good thing. Might raise the price tag a bit. I know the aluminum ones are much more costly. I'd like to try making some fiberglass ones.
The attached image is me messing around with a 3D modeling program. I thought It might help to model the various frame types for discussion purposes this is my first, details-missing attempt.

blake52
123 posts
17 Dec 2010 3:06AM
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Seagull makes the 26inch wheels 291,02 euros without bearings, FOB France according to matthieu@seagull.fr yesterday. I have inquired about IMAC wheels a couple of times in the last few years and never got an answer.
Blake

Hiko
1229 posts
17 Dec 2010 5:08AM
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Those 3d programs look great!
Makes my back of an envelope chicken scratchings look real bad

Clemco
430 posts
17 Dec 2010 7:10AM
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blake52 said...

Seagull makes the 26inch wheels 291,02 euros without bearings, FOB France according to matthieu@seagull.fr yesterday. I have inquired about IMAC wheels a couple of times in the last few years and never got an answer.
Blake


291 euro! Thats NZ$520 at todays rate. The Imac 19" were NZ$350+tax each but that was over 10yrs ago. They would be at least $500 now. They weigh 4.5kg. The 26" probably weigh 5kg. Yes fibreglass sounds like the way to go if you have the time and the skills.
I guess Class 5 is more suited to the design and build type blokes. That's what attracted me to the class. Warning! It can become an addition once you get into it.
Nice 3D Blake. That's pretty much the plan I am working on. What cad program are you using?

blake52
123 posts
17 Dec 2010 8:21AM
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Clemco,
yeah, it is roughly from your sketch. Strata 3D CS 5.5 not really cad, but makes nice images and of course allows the model to be rotated. It is pretty labor intensive at first, but then changes are easy. It now has a mast and forks...


Blake

Clemco
430 posts
17 Dec 2010 10:34AM
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You must have esp Blake. This is the plan I was working on last night.
Note I have moved the mast post slightly forward from the last sketch.
The main steel frame will sit flat on a bench when turned upside-down.
Makes it easy to make a temporary welding jig like I did with the Mini.
How do you like the new name?






blake52
123 posts
17 Dec 2010 1:06PM
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I like the name. Which part sits flat on the bench? I know that sure makes assembling stuff easier, but didn't see much on the same plane. So, what brought about the changes? Moving the mast forward would make the boat heel more (all else being equal), but put more force on the front wheel??? I would really like to measure a bunch of class 5 yachts to see what is different and what is the same. I know that relatively small changes in mast rake on my fed 5 made big differences in handling.

Clemco
430 posts
17 Dec 2010 3:32PM
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Yes, the adjustable mast rake is the important thing. It doesn't really matter where the mast is attached, to a point, as long as you can adjust the rake to bring the center of effort of the sail over the center of where you feel balanced. The old sail I built the yacht for had a shorter foot than the one I am using now. I find the new one needs to be positioned further forward so I can position the pulleys on the boom further back and get more leach tension. The newer sails seem to be designed to be raked back quite a bit. Narrow at the top and a long foot. Could this be for higher speeds?



aus230
WA, 1659 posts
17 Dec 2010 4:18PM
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clem
does that mean if the back wheels are breaking away a bit the mast should be stood up a bit?

Clemco
430 posts
17 Dec 2010 6:08PM
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aus230 said...

clem
does that mean if the back wheels are breaking away a bit the mast should be stood up a bit?


Yes, more than likely...but if the wind is up and you're light like me, you may need to also add some more weight to hold it down .

blake52
123 posts
18 Dec 2010 1:38AM
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About the F578 photo: look at the space between the pilot's face and the boom. The boom on my Rocket clonks me on the helmet if I don't duck. If I could slide back that far (which I can't even with the backrest all the way back) the front wheel would come off the ground just sitting still????
Blake

Hiko
1229 posts
18 Dec 2010 6:14AM
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I am not sure if that setup is within the class5 rules safety wise
It would seem to me that hitting something would give you a full facial with the end of the boom

blake52
123 posts
18 Dec 2010 7:06AM
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which IS a violation of the 5 Promo rules, for just that reason. Promos have a long boom

Clemco
430 posts
18 Dec 2010 9:12AM
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Hiko said...

I am not sure if that setup is within the class5 rules safety wise
It would seem to me that hitting something would give you a full facial with the end of the boom


I wouldn't worry too much about that happening. The end of the boom is all-ways slightly off to the side anyway, and those guys never crash.... they just win the races.

aus230
WA, 1659 posts
18 Dec 2010 9:28AM
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I dont think it breaks any rules.

BOOM
B1. The boom must be made of round section straight metal tube(s).
B2. The lowest point of the boom must never be able to come below :
or : 1/ 45 cm from the ground
or : 2/ eye level
whichever is highest.
There must be a device to make it impossible to sheet any part of the boom below this level.
A note of the minimum distance between the lowest point of the boom and the yacht is made for future checking and the position at which the measurement was made is marked on the yacht and the boom. [F.G.A. 26/9/94]


I had aus230 set up like the pic, but found the front way to light and had to move my body foward 10" to get controll of the yacht.

Cheers
Vic

Hiko
1229 posts
18 Dec 2010 9:53AM
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Sorry I disagree The boom is not always off to the side especially when tacking or gybing secondly a front on impact would most likely pivot the torso upward putting the end of a short boom right in the face
Regardless of any rules it looks a hazard to me having a boom that short
It is quite conceivable that an impact could swing the yacht and the boom
creating a danger to the head even if the boom was off to the side originally

blake52
123 posts
18 Dec 2010 10:38AM
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Hiko,
apparently the Belgians agree with you. Despite the rule AUS230 posted, which I think is current, they were checking yachts to be sure the boom cleared the pilot's helmet when block to block. I don't know what they were doing with short booms that didn't even pass over the head.
dangerous is not always against the rules...or class 5 might be banned altogether[}:)]
Blake

Hiko
1229 posts
18 Dec 2010 12:13PM
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Yes you are right if we wanted total safety we wouldnt do much at all
and even then we wouldnt be
Not that keen on looking for trouble though I hate pain-- it hurts

Test pilot 1
WA, 1430 posts
18 Dec 2010 5:53PM
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The "good' thing about pain...... it lets you know that you are alive...still [}:)]

landyacht
WA, 5921 posts
19 Dec 2010 6:21PM
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that boom position lets you know your finally starting to build a decently fast class 5
mind you at least ive got a seatbelt. the lowest this boom will go is 460mm, with an eye level of 400mm( got checked earlier this year)

landyacht
WA, 5921 posts
19 Dec 2010 6:25PM
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blake52 said...



These photos are from this year's worlds 2010

the pilot of F225 must be rather short as his body has to be visible from above and hes got an awful lot of nose covering on that yacht, not unlike that blue YOTT that seems to have a fairing going wayyyyy back to

blake52
123 posts
20 Dec 2010 1:25AM
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I have wondered about those nose fairings...my feet, which the rules say have to be visible from above go way forward of the Y on my Rocket YOTT. Maybe the Y is further forward on the French boats. I found a mast top photo of a Plume yacht, I think from the Worlds in Argentina. Feet just visible. I'm searching for a similar photo of a British YOTT boat.



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"Class Five Design" started by blake52