New Posts New Posts RSS Feed: Ovington Laser
  FAQ FAQ  Forum Search   Register Register  Login Login

Ovington Laser

 Post Reply Post Reply Page  <1 2345>
Author
tink View Drop Down
Really should get out more
Really should get out more


Joined: 23 Jan 16
Location: North Hants
Online Status: Offline
Posts: 507
Post Options Post Options   Quote tink Quote  Post ReplyReply Direct Link To This Post Posted: 31 Mar 20 at 8:34pm
Originally posted by Riv

Wow, that is a lot of tolerance  in the fit between the mast pot and the step. I assume it was designed like that initially to make it really easy to fit the deck and hull together.

Maybe some hull and deck moulds needed this much tolerance to fit because they were built to a wide tolerance in the first place.

There now is absolutely no need for this much tolerance. If they are all like this then I'm not suprised mast rake is a problem.

It's a shame old Lasers don't get sawn up much as this would have been sorted out years ago.

I think it probably took off so fast that though it could have been sorted it would have suddenly made an awful lot of boats uncompetitive plus probably back then no one was complaining.

Iím sure it is (I said this earlier) to build the boat to the manual with an optimal mast rake. 
Tink
https://tinkboats.wordpress.com/

http://proasail.blogspot.com
Back to Top
Sam.Spoons View Drop Down
Really should get out more
Really should get out more


Joined: 07 Mar 12
Location: Manchester UK
Online Status: Offline
Posts: 2670
Post Options Post Options   Quote Sam.Spoons Quote  Post ReplyReply Direct Link To This Post Posted: 31 Mar 20 at 10:19pm
Given that mast rake, on boats that can adjust to taste, varies by loads I wonder how the Laser has had an optimum/ideal rake for 40 odd years?
Spice 346 "Flat Broke"
Blaze 671 "supersonic soap dish"
Back to Top
GybeFunny View Drop Down
Far too distracted from work
Far too distracted from work


Joined: 27 Oct 09
Online Status: Offline
Posts: 360
Post Options Post Options   Quote GybeFunny Quote  Post ReplyReply Direct Link To This Post Posted: 01 Apr 20 at 6:55am
Thanks for sharing that mast step photo, very interesting. My first laser sail number 63k sailed very well but when I upgraded to a 144k boat it was a pig to sail, it screwed up into wind in every gust. I compared the mast rakes and the 144k boat had a considerable amount of extra rake. I have had 2 other boats over the years which had the normal mast rake so in my very limited experience 25% of Lasers are bad, I am certain Ovington can improve that rate!
Back to Top
GybeFunny View Drop Down
Far too distracted from work
Far too distracted from work


Joined: 27 Oct 09
Online Status: Offline
Posts: 360
Post Options Post Options   Quote GybeFunny Quote  Post ReplyReply Direct Link To This Post Posted: 01 Apr 20 at 6:56am
Originally posted by Sam.Spoons

Given that mast rake, on boats that can adjust to taste, varies by loads I wonder how the Laser has had an optimum/ideal rake for 40 odd years?
Presumably as it has had the same sail cut and spars for most of those years.


Edited by GybeFunny - 01 Apr 20 at 6:57am
Back to Top
Rupert View Drop Down
Really should get out more
Really should get out more


Joined: 11 Aug 04
Location: Whitefriars sc
Online Status: Offline
Posts: 8515
Post Options Post Options   Quote Rupert Quote  Post ReplyReply Direct Link To This Post Posted: 01 Apr 20 at 7:19am
The new kicker will have changed the optimum (I'd guess to more upright, as it's now possible to get the boom beyond block to block), and more aggressive squad sailing styles will have altered it too.
Firefly 2324, Lightning 130, Puffin 229, Minisail 3446
Back to Top
CT249 View Drop Down
Far too distracted from work
Far too distracted from work


Joined: 08 Jul 06
Online Status: Offline
Posts: 322
Post Options Post Options   Quote CT249 Quote  Post ReplyReply Direct Link To This Post Posted: 01 Apr 20 at 8:36am
As I understand it, the tolerance around the mast cup in the bottom of the hull is irrelevant.  The mast rake is set by the mast tube, which is held in a jig while it and the deck are being laid up.  The gap between the plywood of the mast cup and the mast tube is filled with bog, and when the hull and deck are brought together the bog can slop around - the mast tube angle is not affected by the mast cup position.

From personal experience the top people (ie world champs and Olympians) in Lasers worry less about production variations than the people in the other SMODs I sail.  I'm not denying that LPE may have problems but that is a problem with one manufacturer, just as the J/24s had problems with Italian manufacturers, RS had a problem with Brazilian (?) manufacture, etc.

I think that Sam is on the money when he notes that it's unlikely that there is only one ideal rake, given the difference in sails, vang power, people, rigs, conditions etc.  I sail way inland and have to dial in far more twist than when on the coast. My arch rival (3 time world Masters champ etc) back in the day used a lot less vang upwind in a breeze than I did.  The top sailors have a very different style than most people so the leach tension that applies to one group is unlikely to be optimum for the other, etc etc etc.


Edited by CT249 - 01 Apr 20 at 8:37am
Back to Top
Riv View Drop Down
Far too distracted from work
Far too distracted from work


Joined: 23 Nov 13
Location: South Devon
Online Status: Offline
Posts: 270
Post Options Post Options   Quote Riv Quote  Post ReplyReply Direct Link To This Post Posted: 01 Apr 20 at 11:35am
I have not expressed myself clearly.

The mould builders decided upon a larger diameter cup in the hull than the bottom of the mast pot (looks about 15mm to me)

They did this for a reason. What would the reason be? I can only think that boats were being produced in several moulds all slightly different (+/- 7mm) and this level of tolerance allowed all the hulls and decks to fit and so reduce waste, improving profit.

This means that the fore and aft position of the mast pot was +/- 7mm. Would this make a difference?

To produce Lasers quickly how many moulds were used? 5 hull and 5 deck moulds? Given the horizontal tolerance how accurate were mast pot rake tolerances?

The other option is that the fore and aft measurements were always spot on but the mast pot rake measurement was the one that was out. This I feel is more likely. as it is more difficult to check than the fore and aft position.

On a similar subject who has used the knot method of reducing mast rake on a Laser for windy conditions?
Mistral Div II prototype board, Original Windsurfer, Alpha 220PR
Back to Top
JimC View Drop Down
Really should get out more
Really should get out more
Avatar

Joined: 17 May 04
Location: United Kingdom
Online Status: Offline
Posts: 6225
Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 01 Apr 20 at 12:30pm
I dunno folks, I think you're making a storm out of nothing. That the Laser construction is a bit agricultural is no suprise.

The mast rake relative to the deck must be controlled by the deck moulding. That's surely going to be long cured and rigid by the time the deck and hull are joined. As for the mast rake relative to the hull mould, its going to be difficult for that to vary much, because there won't be more than a few mm variance if the two mouldings are going to meet at bow and transom.

So why a great big cup? Think about it. You want to get the pot in the cup first time, its very fiddly to align what you can't see. So a great big pot and its almost impossible to get it wrong. If mast rake varies significantly I would be reasonably confident it was an issue with the deck moulding process.
Back to Top
Granite View Drop Down
Far too distracted from work
Far too distracted from work
Avatar

Joined: 12 May 04
Location: Scotland
Online Status: Offline
Posts: 473
Post Options Post Options   Quote Granite Quote  Post ReplyReply Direct Link To This Post Posted: 01 Apr 20 at 1:01pm
The rake of the mast tube will be set in the deck mould, and there could be some variance there, particularly if the mast tube is a seperate part of the mould from the rest of the deck. However I think the bigger risk comes from assembly.

Depending how stiff the deck is prior to joining it would be possible to introduce some variance. Potentially if the mast tube went into the pot at the back edge, and then as it was pushed down the deck moulding slid forward as the gunwhales aligned this could distort the deck moulding giving a different rake than if the deck moulding started at the front and slid back. 

It could be controlled with assembly jigs or with strict procedures but if it just relies on procedures it certainly opens the possibility for variation depending on the workforce.
 




Edited by Granite - 01 Apr 20 at 1:08pm
If it doesn't break it's too heavy; if it does it wasn't built right
Back to Top
Rupert View Drop Down
Really should get out more
Really should get out more


Joined: 11 Aug 04
Location: Whitefriars sc
Online Status: Offline
Posts: 8515
Post Options Post Options   Quote Rupert Quote  Post ReplyReply Direct Link To This Post Posted: 01 Apr 20 at 3:05pm
Can someone give an idea of how far out mast tips can be from one another? From that we should be able to work out how many mm the pots are actually.
Firefly 2324, Lightning 130, Puffin 229, Minisail 3446
Back to Top
 Post Reply Post Reply Page  <1 2345>

Forum Jump Forum Permissions View Drop Down

Bulletin Board Software by Web Wiz Forums® version 9.665y
Copyright ©2001-2010 Web Wiz
Change your personal settings, or read our privacy policy