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-   -   Am I right about the mast foot position all the way back on an F-type? (http://www.star-board-windsurfing.com/forum/showthread.php?t=2126)

Guest 23rd June 2007 04:10 AM

Am I right about the mast foot position all the way back on an F-type?
 
Hey, just for fun I played with different mast positions on my FT 148 (10.0 sail) and guess what - when I set it all the way back the board felt like somebody unsticked it from the water! What a difference!
Although the wind was just a little too light to plane, I felt the board is almost getting on a plane when I was pumping (which also got easier btw). Few pumps and although I did not get on a full plane I was quite suprised to see how far I got from the shore in notime.
Can't wait to try it tomorrow with maybe a little stronger wind.

I found out that with my weight (200 lbs/90kg) and this large rig my nose tends to stay very flat in _low winds_ and I have to be careful all the time not to dive it under water.

So I wonder what are your comments about it.
I found this comment on rec.windsurfing about GO and large sails needing mast way back so that you ride it on its tail as it was supposedly designed:
http://groups.google.pl/group/rec.windsurfing/browse_thread/thread/c69beca7d5b6ac9d/0c404c3f97e5c4adl#0c404c3f97e5c4ad
What do you think?

And second question - how would that change with stronger winds? Should I move it forward then?

-marek

o2bnme 23rd June 2007 05:47 AM

RE: Am I right about the mast foot position all the way back on an F-type?
 
The more I sail my FT148, the more I realize I like the mast track all the way back. I haven't moved it from this location in well over a year. I use a 9.8 v8 on it the most. The other sail is an 8.0. I've found I can control things just fine from that position. I'm only 145 lbs/65kg. So, I guess this combo works for all sizes.

I've found I like using a large fin on my FT148, but I'm about to get some smaller fins to play around with. I want to be sure I'm not using too much fin when the wind picks up. For the lightest of lightwind days, I have an R14S. This has been a great find for me. I can plane in next to no wind.

The other day, I was using my FT148/9.8V8 combo with a R13M 68cm fin. The wind was probably <15mph. I got the board up over 25mph. I thought this was a pretty good showing with that big of a fin.

The only time you should move the mast forward is when you can&#39;t keep the board down (tailwalking). I find that I can swing my body weight more to the mast when I&#39;m about to tailwalk and this counteracts things for the most part.

Guest 23rd June 2007 01:58 PM

RE: Am I right about the mast foot position all the way back on an F-type?
 
o2bnme, you rock! :-)

Just getting my morning coffe and off I go. Live is beautiful on Saturday.
Thanks,

-marek

P.S. R14S - can you give a link as I don&#39;t see it on a Drake website?
P.S.2. Do you think I would be able to get on plane on 10 knots with my weight and setup?

Roger 23rd June 2007 10:35 PM

RE: Am I right about the mast foot position all the way back on an F-type?
 
Hi Marek,
Yes, with the right fin (the Deboichet custom R14 Soft in 68-70 cm might be the right fin for a larger sailor like you) you could probably expect to plane reasonably easily in a steady solid 10 knots of wind with a properly tuned (for marginal conditions) 10.0 m2 rig.
Hope this helps,

Roger 23rd June 2007 10:40 PM

RE: Am I right about the mast foot position all the way back on an F-type?
 
Hi again Marek,
Here&#39;s the link:
http://www.deboichetcustom.com/

bensen 24th June 2007 12:16 AM

RE: Am I right about the mast foot position all the way back on an F-type?
 
Hi Roger

What about the Apollo 75cm fin on a F-type 158? Will it offer early planing, or will it be overfinned?

Any guess?

Best regards

Bensen
http://www.bensens.dk

Roger 24th June 2007 10:00 AM

RE: Am I right about the mast foot position all the way back on an F-type?
 
Hi Bensen,
I think you would be seriously overfinned.
There&#39;s a ratio/relationship between board width, tail width,
and fin span.
If you go too big, you might get planing early, but you won&#39;t be planing fast, and control issues will "appear" before the board can get up to full speed.
If the wind stays < 12, a super big fin can work, but once you get the board fully lit up, the drag of the big fin will slow you down, and at some point will become hard to control.
I sailed the Apollo this evening with a 39 cm Tangent Dynamics weed fin, and I was able to plane in about 10-11 knots with the 7.5 Severne Glide, but a 39 cm fin on a board with a tailwidth of almost 100 cm makes for some serious control issues.
So, the board width/tailwidth/fin span equation works both ways.
Too much fin span is not good, and too little fin span is also not good.
I didn&#39;t spin out, but found it difficult to keep the Apollo from wanting to head upwind, (lots of front foot pressure and unraking the rig required to bear off at all).
But, when sailing in the Pamlico Sound, over the 40 cm deep sandbars,
you have to use a fin that isn&#39;t going to drag on the bottom or you&#39;ll get "pitched" violently over the front. Been there, done that.
In summary, the 75 cm Apollo fin would be too large for the F-Type 158
I found the stock fin was pretty good on the F-Types, and I would use Deboichet Concepts up to around 66 cm on that board.
Hope this helps,

Guest 24th June 2007 02:26 PM

RE: Am I right about the mast foot position all the way back on an F-type?
 
Well, I tried the new setup and yes, in lightish winds it seems to help and pumping was effective, but when the wind suddenly picked up (very strong and uncomfortable gusts) I had to sail to the nearest shore and move the mast foot forward as I couldn&#39;t stop the board from going upwind (what&#39;s the solution for that anyway, sheet in despite of the strong wind?).

Another question for which I&#39;d love to get an answer - in the stronger winds I find it difficult to sheet in (and thus I go slow despite of the strong wind) due to the fact, that when I lean on the side to balance the powered sail I cannot get enough mast foot presure (cause my front foot work to the side, not forward) and the board goes upwind.
So I change my stance to face more forward, push with my front foot but then I cannot sheet in.
What do I do wrong?

Grant 24th June 2007 07:05 PM

RE: Am I right about the mast foot position all the way back on an F-type?
 
I would think that the size of sail and size of skeg are balanced by mast foot position. I am more confortable and I believe faster when the mast foot position is placed closed to the front with big sails and bigger fins. A good way to experiment isto have a buddy who is as fast as you not change anything while you chance mast foot position only, several times just to see what difference it makes.

Cheers,

Grant

Roger 24th June 2007 08:00 PM

RE: Am I right about the mast foot position all the way back on an F-type?
 
Hi Guest/Marek,
If the wind has huge gusts (more than 5 knots higher than the ambient wind) you may be simply overpowered. That requires a change to a smaller rig, or some serious tuning of your existing rig to depower it.
If you can&#39;t sheet in, you can&#39;t put your weight on the rig.
With no weight on the rig, 2 things happen.
You don&#39;t get any mast foot pressure, and your weight goes right on the upwind rail.
So, the board does precisely what you are telling it to do.
No mast foot pressure to drive the nose down, causes your board to turn upwind.
Weight on the upwind rail tips the board to windward (windward rail lower than the downwind rail) and the board follows the rockerline upwind due to the shape of the bottom.
Flatten your sail out (more downhaul and more outhaul to reduce it&#39;s power and increase the twist at the top of the sail) and you may be able to sheet in OK, and then you can commit all your weight onto the rig, via the harness lines, and get your weight off the upwind rail and back onto the rig, driving the board through the mast foot.
Then you can use your legs and feet to adjust the roll angle of your board so you go straight ahead, on a beam reach; upwind by lifting with your front foot and pushing across the top of the fin with your back foot; or down wind by unraking your sail slightly and pushing with the heel of your front foot to "push" the nose of the board off the wind.
Hope this helps,


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