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View Full Version : Am I right about the mast foot position all the way back on an F-type?


Guest
23rd June 2007, 04:10 AM
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
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
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
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
Hi again Marek,
Here&#39;s the link:
http://www.deboichetcustom.com/

bensen
24th June 2007, 12:16 AM
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
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
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
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
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,

Terje
25th June 2007, 03:51 AM
Hi all,

Very interesting info from your tuning of the FT148.

I have a FT 138 that I ride with a 8.4 + 52cm stock fin (rider = 68kg)
The mast foot is located in the middle of the box.

With this setting, the board is going up wind very easily, too much I would say, as I have great difficulties to make it going downwind.
When going down wind the nose of the board is low and is frequently catching some chops. I am in a very instable position, strongly pull forward and in a fear to be catapulted.
I tried to move the mast foot all the way backward ==>I was doing lost of spinout, with my front foot intending to extit the strap. Not so ggod.

Which setting would you recommand to adjust ?

Thanks,

Terje

Guest
25th June 2007, 04:15 AM
If you feel like you have to push the rig towards the nose to keep from going upwind chances are you lines are too far forward (sometimes your front foot wants to exit the straps??) (-> lines further back, helps you going downwind as well).
FT138 MF all the way back, boom chin high.
BTW fear of getting catapulted == good, just make sure it doesn&#39;t happen.

o2bnme
25th June 2007, 09:47 AM
Guest wrote:
If you feel like you have to push the rig towards the nose to keep from going upwind chances are you lines are too far forward (sometimes your front foot wants to exit the straps??) (-> lines further back, helps you going downwind as well).
FT138 MF all the way back, boom chin high.
BTW fear of getting catapulted == good, just make sure it doesn&#39;t happen.

I tend to agree. I am 65kg and have stopped putting my mast foot forward at all. I always leave it as far back as possible. If the board takes off, I&#39;m getting better at controlling this situation ... I can push the rail down by leaning forward and putting weight on the front foot. Even when I lean forward, though, I am primarily putting weight on my back foot. This is because I tend to sail with a larger fin to be sure I can get through the lulls.

Terje
25th June 2007, 06:09 PM
Guest wrote:
FT138 MF all the way back, boom chin high.


I tried the mast foot all the way back : my front foot was going out of the strap. But it was quite windy for the 8,4 sail, and my line were maybe to forward.
I will experiment with the lines further back.

And concerning the strap position, what would you suggest ?
At the time, I still can move them backwards (one hole left behind).

Terje

kimax
27th June 2007, 11:55 PM
2Terje: Longer harness lines makes it easier to go downwind, I&#39;ve just tried it two days ago (I have adjustable). I was surprised how much more control I gained when making them longer in downwind sailing. ;)

Guest
28th June 2007, 11:20 PM
lines further back is of course only part of the equation, 28+ lines too
center of gravity to your advantage!

Terje
29th June 2007, 11:31 PM
I tried new setting yesterday, during a cool session 10/14kts, 8,4m² on FT-138.
First I moved back the harness line --> the sail was more balanced in the upper range.
Then, I move back the straps (now on the latest hole) and the mast foot --> board seems to higher on the water, catching less chops and be globally quicker. Noticable improvement.
The only drawback may be an increase pressure on the back foot and a front foot that intend to exit the strap.
Maybe I have to change my position on the board to be more on the front foot.

Terje

Guest
30th June 2007, 12:48 AM
- waist harness?? (YES!)
- harness lines 28++ (YES!)
- turn into the direction you want to surf
- lean forward
problem with a bit of exercise will go away by itself.

Get GPS to validate your "feelings" (sometimes its feels fast but is really slow)!

Terje
2nd July 2007, 02:42 AM
I use :

- waist harness?? --> yes

- harness lines 28++ --> 22. And it seems long enought for me. I should try an adjustable set to be more at ease when going down wind

- turn into the direction you want to surf --> You mean turn the upper part of the body in where I want to go ?

- lean forward -->I try !

Terje