I am hearing that a "Low" spin pole puts inward stress on the bows. I sail a Mystere 5.5 and fly a Tornado Spin. I have tried to rake the mast back.. but this effects my helm to much and depowers me to much.

Is this really a serious concern? Anyone ever see a Mystere fail due to this? Should i look into making a foil?

Thanks,

Another pic:

Did you shorten the bridle to lower the pole to lengthen the luff lenght for your chute?

If not... the mystere's usually have a sub deck in the bows ... so you should be good.

Just for grins... where is your spinaker bail... I am surprised the spin luff is not too long.

I think there is more inward pressure put on the bows by the mainsheet loads transmitted through the forestay than placed on the bows by the spin. I guess the addition of the spin loads to the mainsheet tension could be an issue but generally the mainsheet isn't on as hard downwind with the spin as it is upwind.
also, if the boat is meant to have a jib then the angle of the forestay/bridle wires to the hulls will be less so the boat has probably been designed to take that load. On boats that were never meant to have a jib there is generally a much higher meeting of the bridle wires and forestay (like the HT). These boats have more of a problem with the inward loads by a lower lying bridle set up- but they handle spin loads fine.
This is from my experience and having had an issue with structural damage from 2 dudes on the wire at the back of the boat and max mainsheet tension. This was without the spin up.
engineering guys could chime in.

My pole was very high when i used a F18 spin.. i had to lower it alot when i got the Tornado spin to get luff tension on the bigger sail. PS my spin bridal is a cable with line on the ends for adjusting pre-bend / position

Is a "spinnaker bail" the same thing as a tang (more or less)? If so... the picture below (from when i first rigged the f18 spin) shows where the tang is... i have lowered the halyard block by 8" as it made me nervous being so high.... i drilled holes in my mainsail track and ran a line in front of my mast for the block to swivel on and ran a line up to the tang.

The early manufactured P19's did not have a sub-deck in them ... The bridle attachment angles on the standard P19 was 45' .... this makes the engineering calculations really easy ...

Forestay Load X (cos 45')= load (in X axis) "vertical axis"
Forestay Load X (sin 45')= load (in Y axis) "horizontal axis"
ex: Forstay load= 1000lbs Cos45'=.5 sin45'=.5

Therefore Load Y =500lbs

Now I had repaired several P19's for some of my friends that had developed ripples/waves just in front of the frontcrossbar on the inside from what I believed to be horizontal loading of the hulls. Therefore when I converted my P19 to a MX rig I installed a N6.0NA bowfoil that changed the bridle attachment angle from 45's to 15's ... this GREATLY reduced the horizontal loading. The boat is much stiffer and does not "paddle foot" over waves but drives straight through. The "issue" is that w/ the bowfoil you must carry the spin-pole fairly low. I haven't scooped any waves (yet) but I have limited visiblity to leeward w/ the chute up. Combined w/ no snuffer system (yet) I use the boat w/ spin for "Distance" races and not "Bouys" races.

For bouy races I race her as a "sloop" rig w/ the bowfoil, this allows me to have higher mainsheet tension so that I can control the MX Squaretop Mainsail w/ a 8x1 mainsheet stack ..... No ripples yet on the inner bows!!!!

To make room w/ the bowfoil for the "MX" jib's hoist hieght I had Randy Smythe make the my jib 5" shorter of the standard MX on the luff length. It has worked out well and I still have my "downhaul" on my jib to adjust my luff tension "on the water" also.

Please note that my spinpole is a carbon fiber windsurfer mast, w/ 6" of prebend. I could use a straight 2" aluminum tube and adjust my spin bail up the mast, maybe gaining some visiblity ... but when the boat is heeled over I don't think I will really gain that much visiblity and I just don't like the visual of a 2" aluminum tube sticking out in front .... IT LOOKS LIKE SOME MAD PLUMBING JOB GONE WRONG !!!!

Sail Flat, Sail Fast, Sail Safe
Harry Murphey
TheMightyHobie18/#9458, Fleet54/Div11
P19MX/#86, CRAC

You could do with a compression tube as used on the Condor 16/Hurricane 4.9. If I recall correctly this was a 1" od tube with a 1/4" wall and had tube end pieces(solid) that had a groove that slotted over the bridle tangs which were at 90 degrees to the hull. If yours are as suspected in line with the hull you could look to carefully drill through the tube and attach with a large bow shackle which would also be used to attach the bridle. The advantage of this arrangement is that it cannot 'capsize' like the nacra flying foil which leads to expensive breakages.

http://www.catsailor.com/gallery/displayimage.php?album=lastupby&cat=0&pos=1

http://www.catsailor.com/gallery/displayimage.php?album=lastupby&cat=0&pos=2

Cheshirecatman

I need to take some PIC's and post them ... but I'm technically challenged when it comes to computers.

My bowfoil is rigged 10" above a straight line from bow-to- bow w/ a 1" downward pre-bend in the middle. I paid $220.00 for the foil from Performance Cat at the time and $50.00 for the windsurfer mast. My friend made his bowfoil from a broken section of a INTER 20 mast for minimal $$$$'s

My spinnacker is a 25sqM (all white) Zuccolli Tornado Chute that Robbie Daniels sold me ... it is rigged to be "snuffed" but I just haven't gotten my lazy butt around to fabricating a snuffer system

It's not perfect and has more strings to keep it in column then I like ... but it works ....

What's the old rule .... when you get your boat perfect it's time to sell it and start over ....

Thanks for the ideas
Harry

Actually cos(45 deg) = root 2/2 = approx. 0.707.
Coincidentally, sin (45 deg) also = root2/2.

Just being anal,
D. Ho
TheMightyHobie18 1067

It's been almost 30 years since I graduated from college w/ an engineering degree .... I quess I should have dug out one of my old textbooks and verified the numbers !!!! But I did remember that the sin and cos of 45' are equal ....

So in the example, instead of a calculated load in the Horizontal Axis of "Y" =500lbs given the forestay load is 1000lbs it is actually "Y" = 707lbs

That may make my point even better .... Thanks

As you may have quessed ... I wasn't the most brilliant person in my class !!!! On one test I reduced 4/2 to 1/2 ... the Prof circled that one along w/ a BIG ???? I was able to argue for partial credit, that it was a simple (but stupid) mathmatical error and I had used the proper engineering principle/theory ... the prof was in a forgiving mood that day ....

What year is your TheMightyHobie18??? That is one low sail# you have there. I have two TheMightyHobie18 Mainsails, the one I race is #9458 which I just transfered to a new set of sails last year, the other is #1400 ... I haven't seen any lowwer then my ol' #1400 in a long time.

Harry Murphey
TheMightyHobie18/#9458, Fleet54/Div11
P19MX/#86, CRAC

Yes, my TheMightyHobie18 is one of the older ones. It's a 1978. I think the first ones came out in '77 or '76.

D.Ho
TheMightyHobie18 1067

Sooooo... if i read this all correctly.... as long as i dont have a 707 lb crew member sitting atop my mast, and an unladen african swallow doesn't drop a coconut on my spinnaker, i should be ok with my setup?

but what if there were TWO unladen african swallows? Maybe they could tie it between them?

wait African swallow or european swallow?

I don't know!

Don't forget about the KILLER BUNNY lurking up at "A" Mark ......

Whats your favorite colour?

Blue....NO, Yellow!

Aaaaaaaaarrrrrrrrrrrgggggggghhhhh