Wanting to put a bridle foil on my 5.2 to reduce the bow loads with a spin. Will a 5.8 foil fit my 5.2. Ive got all the parts to finally put a spin on the boat, however did not want to do so until I could get a foil. If anyone has a 5.8 foil they could measure, I need the width measurment. I sure would appriciate it.
Thanks

FYI I have a 17.5m2 spin on my 5.2 with no bridle foil. Been there for 3 years, no adverse effect I can see.

Look for a 5.5 foil. The 5.8 and 6.0 are the same and would be too wide. for the 5.2. Hell, It's almost too wide for the 5.8 in my opinion.

The 5.5 and the 6.0 have an 8' 6" beam, the 5.2 and the 5.8 have an 8' beam. The foil from the 5.8 would be better.

I think the spin puts only a small amount of inward pull on the bows when compared with the inward pull from the forestay bridle. Especially since when running down you generally don't have the mainsheet cranked on as hard as if you were heading upwind. All that force in the mainsheet blocks really tension the forestay... and can lead to problems.

The bow foil on a 5.8 measures 70".
Buzz

And a N6.0NA Bowfoil is 70" long also.

I installed one on my P19 when I went to the MX sailplan. And the biggest improvement has been in upwind performance. I can sheet the main tight enough to "stand the leach" up and control the squaretop mainsail. She drives straight through waves and does not "paddlefoot" over the waves.

Now I have done something I haven't seen anyone else do ... using 1/8" spectra I have tied cross bracing from the bridle tangs over to the bowfoil on the opposite side, this is so the foil is "locked" in place on the centerline of the boat

Harry

Are you sure that doesn't dramatically increase the sideways load on the windward hull? Maybe I don't get it (I'm no expert) but I wouldn't want to see you damage your boat. I may be crazy but to me it sounds like you are defeating the purpose of the foil altogether!

I did the same thing on my 5.8 when I put the spin pole on. I also have a line from the pole to the foil which keeps the foil from moving aft when the jib is sheeted hard.

Dennis,

It has to do with "angles" ... a stock P19's bridle attachment angles are Vert = 45* and Horz = 45*. On my boat currently the vert = 75* and horz = 15*.

So the forestay load is much more vertically orientated. The two 1/8" spectra lines do not carry any of the load directly, but only hold the foil in it's proper location and the foil itself carries the load.

The 5.5 has a narrower foil.

Ok how long is the 5.5 foil compared to the 5.8. A 70" foil
will fit the 5.2. Both foils are available, the 5.5 from
KOsailing the 5.8 from Murrys. Foils are within $10.00 of each other. The reason I would like a foil is I know of 2
5.2s which had hull failures when flying a spin. Both
boats granted were 25 to 30 yrs old, & never designed for a
spin. Neither had a foil, and still a foil may not prevent a failure in a 30 yr old boat. In looking on line the 5.5 does appear narrower, if the length is right (70" or less) I'll go with that one, if not the 5.8 will fit. I greatly
appriciate(sp) all the input. As I believe the only stupid
question, is the one not asked.
Thanks

Are you building this 5.2 to sail single handed with the chute?

You probably have enough power in the main so you might want to add the chute like the F18HT or the Marstom M20 or CFR 20 or like the F16's/F17's going uni.

This allows you to split the forestays into two and put your pole anywhere you want in the fore triangle. The bridal foil is designed to deal with the increased loads induced when you oversize the jib and so you lower it's tack point. I don't think it is a great way to go.

I would bet that the 5.2 failures were caused by a lack of attention to the front beam, dolphin striker and how it seats in the hulls. If I remember, they use the steel straps and alu beams and after 30 years... this was probably not a happy marriage!

At any rate...This game is all about luff length of the spin.

The shorter the spin luff.. the higher the pole can be... the smaller the squeeze on the bow.... and the slower the spin is...

But.. you rake the mast aft as far as you can... (bitch to get under boom)... you are limited by the mast base (able to still rotate) and your ability to rake the rudders under the boat. This gives you max upwind performance. You want the rig to be balanced.

Pick a safe height on the mast for the hoist height bale/line limiter.
(max half way from hounds to tip... safe = 1/3 way hounds to tip. If you use a 10 - 12 foot pole... you can find that alu extrusion lots of places. Use an F16 spin and you are good to go.

You should be able to get the proper tension on the spin luff and have enough prebend in the pole induced by the pole front stays.

When you use the foil... you are setting max height of the pole in the middle of the pole by the length of the bridle foil wires. Now you have to induce some prebend in the pole by tensioning the stays from the bow tips to the pole tip. This will really tow in your bows... or you need to build a pole strut to induce the needed prebend and just use the pole stays to keep the tip centered and in column.

Have fun
Mark

The boat will be singlehanded some of the time, otherwise with the all 90 lbs of my daughter as crew. Mainly club racing Friday evenings. My thought with the foil was to
continue to use the small jib with the foil set below the height of the present bridle wires. But at a height which would still allow proper sheeting. Kite is same size as F16. Pole is carbon 12 ft sail board mast(two piece)tapers from 2.5" to 1". I also have an Alum 1" pole 12' but felt the carbon would be stronger. Was planning on setting the pole like the F18ht bringing all lines to current position of the bridle wires. Setting the mast height between the spreader & tip. May change to a third of the way. I will probably add a furler at a later date so as to be able to decrease sail area forward.

Both 5.2 hull failures were forward of the front beam at the
bulkhead. I attributed this to the pole height being to high
& pulling the bows into the center?? One spin may have been oversize for the boat.

My thought was by adding a foil I could decrease this pull to center? Distribute the jib/spin load at the foil, which would in turn keep the hulls with limited toe in. Less stress at the main beam. Wrong thinking?

I have taken the time to remove the forward deck & epoxy additional cloth at this bulkhead. Probably over kill on my part.

Thanks

[quote=Rockport]The boat will be singlehanded some of the time, otherwise with the all 90 lbs of my daughter as crew. Mainly club racing Friday evenings. My thought with the foil was to
continue to use the small jib with the foil set below the height of the present bridle wires.

lowering the jib tack will mean you have to move your jib sheeting point

IMO, This is going to be a very busy boat for club racing with the jib. You daughter will be swallowed up with all of the spagetti on the tramp. If you were distance racing... it would be OK.

Unless your club sets a close reach leg every time... I promise the boat will be much more fun with main and spin. The only way to clean up the deck is with a self tacker... $$$ which also requires a re cut jib $$.

But at a height which would still allow proper sheeting.

lowering the jib tack will mean you have to move your jib sheeting point on the tramp and you load up the hulls.

The big big advantage for you with main and spin in club racing is visiblity. If you use the bow foil the chute will be right on the deck and you will not have much visiblity. Very stressful with those laser speed bumps out on the course.

Kite is same size as F16. Pole is carbon 12 ft sail board mast(two piece)tapers from 2.5" to 1". I also have an Alum 1" pole 12' but felt the carbon would be stronger.

Wow... 2.5 inches at the base will be a tough fitting to find for your front beam.

Was planning on setting the pole like the F18ht bringing all lines to current position of the bridle wires.

People drill a hole in the bows because it makes the load needed to prebend the pole tip lower and the angle from the bow tip allows you to keep the pole in column a bit easier. You might reconsider this when you get it all together. A lot has to do with the distance of the front beam relative to the bows and the width of the boat.

Setting the mast height between the spreader & tip. May change to a third of the way. I will probably add a furler at a later date so as to be able to decrease sail area forward.

Both 5.2 hull failures were forward of the front beam at the
bulkhead. I attributed this to the pole height being to high
& pulling the bows into the center?? One spin may have been oversize for the boat.

No... High pole means less load pinching on the bows. The Tornado class specifies a minimum height above the decks for the pole at the plane of the bridal to make sure the boat holds up and the T has a very substantial sub deck.

My thought was by adding a foil I could decrease this pull to center? Distribute the jib/spin load at the foil, which would in turn keep the hulls with limited toe in. Less stress at the main beam. Wrong thinking?

the jib is a bigger load on pinching the bows.. especially when you sheet hard going to weather. Lowering the jib is the worst thing you can do. Also the bridal is not light. It puts weight where you don't want it... on the bows of a boat that has just enough buancy.

I have taken the time to remove the forward deck & epoxy additional cloth at this bulkhead. Probably over kill on my part.

That should do it... nevertheless... You might take the beam off, (it's always good to unbolt the boat every year or so ... just in case you half to do it one year.. frozen bolts are a REAL pain in the butt.

I had my 10 foot wide tornado rigged the way you are going for about a month before I went for the self tacker...there is a lot of string on the boat with a tramp sheeted jib and a spinnaker.

Split the fore bridles at the hounds to your bow tangs., Add a spectra line for the pole center. (Hounds to mid pole which holds pole up) Make sure your pole stays will not allow it to get out of column or rotate with the side stays. Drill some holes in the bows... fill with epoxy, redrill and put some pre bend into the pole with the spectra pole tips stays .. enough so that you can lift the boat with the pole but not invert the pole. you also need this bow tie point for the snuffer hoop the split bridles makes it easier to snuff the midpole chute with no forestay in the way.. It's also easier to jibe with out the bridal to drag the sheets over.

Set the pole tip (with required pre bend) so that you get the right luff tension on the spinaker. you want to be able to grab the luff in your hand and then rotate your hand 90 degrees. Adjust the pole supports accordingly.

with a double ratchet (one at the shroud and one ratchet on the front beam... your daughter should be able to hand hold the spin... A power assist by you when needed can help her out. If you need more power up wind... you could get a square top main which adds back some lost sail area.

Of course... if she drives... you manage the main and spin and you are very fast.

I helped a friend change a nacra 5.8 to a nacra 5.8na and in doing so it was reccomended that we put internal sleeves in the front crossbar (part#2581) and we did so. Was wondering why this was needed.

http://www.catsailor.com/forums/ubbthreads.php?ubb=showflat&Number=164040&page=1

see other post for size of a 5.5 bridle foil

our foil is only 4 and a half feet long "54 inches"

best of luck

Ok Guys,

In order to prove me right, or wrong you need to get a Mechanical Engineering Statics/Beam Loading Analysis Textbook and do some reading. Since I haven't studied this subject in 30 years it's kind of hard to explain the subject matter anymore. (Wouter where are you !!!!) But the difference in a 45*/45* to a 75*/15* bridle attachment angles makes a large difference in the X-axis and Y-axis loadings. (I find I need to make some drawings to analize the problem)

2) Mark's comments about how low the chute is on my P19MX are true ... but like on the "T" you run the chute w/ all the crew wieght aft ... this pulls the bows up and the pole stays clear of the water

3) My pole was also a windsurfer mast ... IMHO a alum PIPE looks like an evil misdirected plumbing job gone wrong. Boats are designed w/ curved lines ... that's what makes them look beautiful. Now I constructed and installed a dolphin striker on my spin pole so I could induce some pre-bend in the spinpole ... I used a section cut from the "butt"end of the windsurfer mast, split it length wise to make the cradle and used a piece of a Hobie Hotstick as the vertical strut, then using 1/8" spectra I tensioned it.

To attach it to the front crossbar I located a old H16 Rudder gudgeon and installed it on the front crossbar. I put a "plug in side of the wind surfer mast and filled the "butt" w/ "MarineTex for approximently 6". Next I carved out the MarineTex so the pole fit over the gudgeon. Using a shortened rudder pin I drilled a hole from side to side through the pole aligning w/ the gudgeon on the front crossbar. Simple and I used alot of "scrounged" parts. Oh, I painted the spinpole white for UV protection and appearence.

3) Nacra Front Crossbar reinforcements: Go out and look at your Nacra ... you will find the following: a round front crossbar .... the dolphin striker ends just at the point where the two hulls meet the crossbar, the dolphinstriker is bolted to the underside of the front crossbar.

Now the mast pushed down on the crossbar (hence the dolphinstriker) .... the hulls push up due to "floatation" ... so what is happening at those 1-2" at the point where the dolphinstriker ends and the inside edge of the hull? The front crossbar is under a concentrated load ... If that front crossbar collapses/kinkes ever so slightly ..... Let's just say the odds are extremely high that you will experience what is called in engineering terms ... "A CATRASTOPHIC FAILURE"

My P19 front crossbar while "wing shaped" and not tubular, shuffers from the same type of failure. And in fact mine did!!!! But there are no factory reinforcements availible for the P19 unlike the Nacra's ... So I took sections of my broken front crossbar ... cut the tramptrack off and DROVE a 18" section on both Port and Starboard sides, inside of my replacement front croassbar so that I reinforced the highly loaded section of my front crossbar. Note I had to use longer bolts to reattach the dolphinstriker and I used some rivets to hold ths reinforcement sections in-place

I've got to run now ... I'm several hours late on leaving to go help w/ Fleet 54's Gunpowder Regatta. Post any questions and I'll answer them when I get home on Sunday

Harry