Mast. Groovy or straight

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Grant Edwards
Posts: 2
Joined: 20 May 2018, 09:12
Design: TS2

Mast. Groovy or straight

Post by Grant Edwards » 20 May 2018, 10:41

I have just bought myself a TS2 IOM that I’m tidying up to do some club racing with. I’m looking at replacing the A rig as it is the one I will use the most and it looks as though it has a fair bit of corrosion on it.
My mast is a straight version with luff ties to attach the sail.
What is the general concencus on straight vs groovy?
I had a look at some videos from the IOM world champs and as far as I could tell they were all running groovy mast with a bolt rope.
Is this the preferred method?

Bruce Andersen
USA NCA Officer
Posts: 759
Joined: 25 Nov 2003, 00:06
Sail number: USA 16
Club: Famous Potatoes Sailin Club
Location: USA 16

Re: Mast. Groovy or straight

Post by Bruce Andersen » 20 May 2018, 18:40

I recall that my TS-2 seemed to work better with a groovy mast and Craig Smith sails. The rig stiffness/spreader position/groovy spar bending characteristics matched the hull's specs quite nicely.

Mine did not go as well with a stiffer, non-groovy spar.

I believe that there was a rig building guide that Craig Smith published that was included with the boats.
Bruce Andersen - USA 16

Grant Edwards
Posts: 2
Joined: 20 May 2018, 09:12
Design: TS2

Re: Mast. Groovy or straight

Post by Grant Edwards » 20 May 2018, 21:36

I went back and had a look at the TS2 setup guide. It does not specifically say whether to use a straight or a groovy mast. In fact some pictures look like a straight and some look groovy.

David Alston
Posts: 9
Joined: 17 Nov 2016, 23:19
Sail number: 11
Club: Bournville
Design: V9

Re: Mast. Groovy or straight

Post by David Alston » 23 May 2018, 02:40

It is my belief that you would be better off with a tubular mast for an A rig no matter what IOM hull.
a/ Lighter
b / You can easily put some controlled pre-bend in it. This is not to say you cannot bend a Groovy mast - you can
c/ Cheaper
The Hound position determines the amount by which the mast flicks off at the top opening the Leech of the Main Sail in a gust as much as how stiff it is. i.e. the height of the fixing point of the Shrouds.

Thoughts on Rig Set-up has advanced a long way since the days of the TS2 just as hull shape has done a 360 since the Nimbus design.
The hull design / shape does not really dictate the rig design apart from determining Hound and Spreader position and length since the chain plate position is determined by the Hull width i.e. a well set up rig works on any boat.

Setting the Hounds 200mm down the mast from the Jib Attachment was virtually unheard of 20 years ago, now it is common place

The lateral stability, the propensity to drift off to leeward, of an IOM is mostly determined by the Fin and Rudder and their relative positions to the mast since the hull itself officers little resistance compared to the fin / rudder once the hull is healed.

Simple answer
Use a tubular mast, a Groovy works well on a C rig. But the mast you have is the mast you have and there is really not going to be a discernible difference in performance.
Sorry no WOW factor - just mm gains if the rig is set to perfection

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