I think it's normal, I've read somewhere advice for speed sailing, "move mast track back till you start spinning out, then move it forward a tad."

With mast foot forward, and board riding flater, you have more board in the water so it's slower.
With mast track back and less board in the water, there's more likely hood of air reaching the fin, so it will ventilate earlier.

It's a compromise of how much back foot pressure you can use and how fast you want to go.
Chop will have a big affect as well, smoother the water less likely to get air under the board.

I usually just run my mast foot 135cm from tail and only move it forward/back 1 to. 3cm depending on conditions. I have a similar set up to you, 114 and a either 6.6 or 7.5. I run a 39cm fin for both sails but find it maybe slightly to small when the wind is on the light side with the 7.5' so maybe excess spin out could be caused by your fin being slightly to small if your useing your 7.5?? Also maybe try and getting more weight through your front leg so you can absorb chop with your bent back leg. I find if I hit chop with my back leg loaded spin out results. Another idea is to put your harness lines back a couple cm( = less force through back leg) I was given this advice when I was having troubles spinning out, made the world of difference. Just some ideas, hope it helps.

I used to own a 115 rocket.

My main fin was a 38cm jp glass fin for 7m+ sail.

This setup used to hammer in light winds, dont think i ever had a spinout on that setup tbh. Also I remember i had the mast track in top 1/3 position.

GusTee said...

Thanks to everyone who replied. I will try the harness lines further back, good point and simple enough. I will get some other fins just to try and see how it responds.

Dark plague, good to compare notes with someone with the same board. A friend that I sail with has a 125 rocket and he has the mast track almost all the way back. I sailed his setup with a 6.6 and his stock 44cm fin and no hints or signs of a spin out.

I've got a 125 rocket with 44cm fin.. I tend to use it in more wind & chop than i should for my weight so have the mastfoot towards the front of the track to make it more controllable. I used to have it at the back and I probably went faster but had some scary moments as the board flew around.I took that as normal until I gave one of the local hotshots a go & he said it was scary!
My 95 Rocket I use with a 30cms fin ( c 20kts) + 26 cm for closer to 25kts. Once again I'm prob using it in too big a chop for my weight so I tend to have the mastfoot forward.I did put it back recently to where they say is ideal but I was out in 20 - 35kts & the board was getting too much air & I got picked up & thrown downwind with a nasty stack.
I don't have much trouble with spinout if I did I moved the lines back a bit & went easier on my back foot.
Pretty sure they are slower with the mast foot forward. When I bought it I was told for optimum speed to aim for the spray to come off no further forward than (?) the front straps when planing (I think)..

Hey GusTee,

Found this article, just adds another point of view, to good points already said by others.

http://www.boardseekermag.com/features/technique/mastfoot-position.html


Kind Regards
Walt

Starting point would be to get a quality fin and then you may well find that the standard fin is just a dud.