Hobie Forums
http://www.hobie.com/au/en/forums/

Hobie 16 Rig settings
http://www.hobie.com/au/en/forums/viewtopic.php?f=14&t=5987		 Page 1 of 1
Author:  Gerry McMahon [ Sat Jan 27, 2007 1:50 pm ]
Post subject:  Hobie 16 Rig settings
Can someone advise on the correct rig settings on H16 ( jibLuff&downhaul ) for various wind strenghts and conditions please.
Thanks Gerry
Author:  mmadge [ Sun Jan 28, 2007 11:08 am ]
Post subject: 
http://www.hobie-cat.net/download/manuels/tuning_16.pdf
Some good set up tips from past world champ
Author:  BobMerrick [ Sun Jan 28, 2007 4:22 pm ]
Post subject:  Mast Rake
I came across this old e-mail exchange with Mike Ingham while cleaning out my e-mail folder. Mike is a really good sailor but new to Hobie 16s. I think it's an interesting perspective from two people who have had most of their sailing experience in other boats. Mike has been a top international level J/24 and Tornado sailor as well as the Thistle North American Champion. The discussion is mostly about mast rake.

Mike:

Bob,
What can you tell me about mast rake?

Bob:

Hey Mike

Here's the deal with rake. The following is what I think works.

In light air it pays to rake back to the point where the jib blocks are about three inches apart. This seems to help pointing quite a bit in the light stuff. I think that one of the biggest reasons is that it lets the jib get flat and twisty. Getting the center of effort back also seems to help pointing quite a bit and in the light stuff you don't need the leech tension.

In the medium stuff you start needing leech tension so you need to pull the rake forward.

In max power conditions I have started going as far forward as 12 inches. In this condition I don't pull that far up because I'm running out of mainsheet. When the rake is around 16 inches and you pull the main hard the mast bends and I can't get the return in the upper leach that I want. When I pull up the rake a few more inches I can get nice return up there. I think it must have to do with the angle of the mast and the sheeting angle. Basically I think the mast just doesn't bend as much.

As soon as you are full power double trapping you don't quite need all that leach return in the top so you can go back to about 14-16 inches and the boat loosens up a bit. My numbers may not be exact. I do it by looking at the main leach.

As you de-power rake helps in the normal way that it helps in every other boat. When it's really windy I set the traveler at the leeward hiking strap and set the rake so that the boat feels good. When I get it right I can make the boat rip with the traveler at the hiking strap and pull it up a few inches if I want height.

Tension is very minor I think. I like it snug in the medium stuff when the rig is max upright. that stops the mast from going sideways and spilling the top of the jib leach. In light and windy stuff twisting the top of the jib is good. I never adjust my side stays.

Bob

Mike:

Bob,
You also say one other curious thing: "As you de-power rake helps in the normal way that it helps in every other boat". How does it help every other boat? Why does raking back work?

Bob:

There are lost of theories but I can't say for sure. I have designed an experiment to figure it out. Some day I'll get it done.
Bob


Mike:

Bob,
The reason I ask is that we did extensive testing in the Tornado and in the end rake did not matter much. We had a CB so I guess that is different than the H16. I am surprised at so much talk about rake, I am surprised (and skeptical) that it makes any difference. I know it affects the jib leads, but it still seems like we could accomplish that other ways.

In the Thistle, we stopped worrying about rake too. I keep it raked relatively foreword in all winds and am fast in all winds.

Now to my theory:
In boats that plane upwind it does make a difference. The first part of the boat is out of the water when planning and the center of resistance moves significantly back because that is the only part in the water. Therefore you want to rake back to get the sail plan back to match the center of effort to the center of resistance.

Cats don't plane, my J24 does not plane, and my Thistle does not plane (upwind anyway), so I can leave the rake alone. I change other things a lot, but not rake.

A 470, 505, V15 all plane so you rake back in breeze.

What do you think?

Bob:

Hey Mike

Yes I have heard that argument before in terms of dinghies vs. keelboats and by extension it makes sense for catamarans. Balance must be part of the dynamic. Still I think there is something more going on. I know that from the 470, where I have the most experience, the boat would noticeably de-power when we raked back. Often the initial rake was accompanied by pulling the jib leads down resulting in no net change to the jib. A few inched of rake would mean the difference between having to luff the main to keep the boat flat to being able to pull the main in with no luffing at all. That has to be more than balance I think.
Some people will tell you that the center of effort gets lower and it does but by such a minimal amount it’s hard to believe that anything gets accomplished. I think it has more to do with changing the effective ratio of the depth to the chord length of the sail. This could be making the sail effectively flatter. (Kind of like driving over a speed bump sideways instead of hitting it head on). I’m not an aerodynamics expert however, but it is damn interesting.
A keel boat can flatten the main with backstay and maybe that’s a better way to do it for them. Do you have a backstay on a Thistle? Following that same argument maybe the downhaul works better on a Tornado.

Bob

Mike:

Bob,
I have heard that theory too.
The J24 main can get as flat as I want with Backstay, maybe even too flat. The Tornado I can get way flat with Cunningham. The Thistle I use shims under the front of the mast step, but that does not bend the top enough, but the bottom 2/3 (which is probably 9/10 of the sail area) is very flat. I think the problem with the Thistle is the main is so big and the leach so long, I can’t rake back significantly, so raking doesn’t do much.
Author:  mmadge [ Sun Jan 28, 2007 7:08 pm ]
Post subject: 
A buddy of mine good div 7 sailor Slim Johnston showed me a quick way of measuring rake.Just measure the distance between the main blocks and the rear crossbeam at the center.18-20 inches seems good in most conditions.
Author:  DougHobie17 [ Sun Jan 28, 2007 8:21 pm ]
Post subject:  Rick's Book
Gerry:

Get "Catamaran Racing for the 90's" There is a whole chapter on the 16. PLUS you will learn a WHOLE lot from it. http://store.catsailor.com/tek9.asp?pg= ... =jqcmhpjpe I also recommend this if you have the money. http://store.catsailor.com/tek9.asp?pg= ... jnrorrrrg4 Will be the best $99 you ever spent.

Good Luck and have fun.

Doug
Author:  John Eaton [ Mon Jan 29, 2007 8:46 am ]
Post subject: 
mmadge wrote:
A buddy of mine good div 7 sailor Slim Johnston showed me a quick way of measuring rake.Just measure the distance between the main blocks and the rear crossbeam at the center.18-20 inches seems good in most conditions.


Can you elaborate on this a bit more please? I'm assuming you (Slim) meant with no load on the blocks? Measured from the boom bail?

Bob, As far as jib block distance I was under the impression that this was obtained by moving the jib up or down the forestay adjuster. Would it be correct to ASSUME that once this position of the jib is established for light air, then raking closes this distance between the jib blocks for heavier conditions?

Great post, thanks :D
Author:  mmadge [ Mon Jan 29, 2007 9:39 am ]
Post subject: 
From the bottom of the boom where the blocks are attached.Yes under no load.
Author:  mmiller [ Mon Jan 29, 2007 10:21 am ]
Post subject:  Re: Rick's Book
DougHobie17 wrote:
Gerry:

Get "Catamaran Racing for the 90's"


Available through an authorized Hobie Dealer... as are the Rick White Videos.
Author:  BobMerrick [ Mon Jan 29, 2007 6:24 pm ]
Post subject: 
John Eaton wrote:

Bob, As far as jib block distance I was under the impression that this was obtained by moving the jib up or down the forestay adjuster. Would it be correct to ASSUME that once this position of the jib is established for light air, then raking closes this distance between the jib blocks for heavier conditions?

Great post, thanks :D


Yes
Both rake and jib height effect your sheeting angle.
I think the main thing I'm trying to say there is that I always keep a little bit of distance between the blocks in reserve just in case I need to go a bit tighter on the sheet.
Author:  DougHobie17 [ Mon Jan 29, 2007 6:51 pm ]
Post subject:  Sorry Matt
Sorry Matt:

I can't pull up links like that on KO Sailing. My local dealer. Yes get them from local Hoibe dealer if you can. They are still worth the money.

Doug
Page 1 of 1 All times are UTC - 8 hours [ DST ]
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/