Advice on Rigging for a Spinnaker

[Stumble]

On your diagram use the track labeled "unused T track" just get a sliding ring that you can attach a ratchet block to and you are done. Ideally you would install a padeye in the correct position which on a trimaran can be tricky. Monohulls are almost never quite as wide as you would want them, a tri can be a little too wide so the typical advice of as far back and outboard as possible doesn't quite work. The exact location depends on the sail, the boat, and the angle of the breeze. For now just use the T track and don't stress over it.

Attaching something lower has the same effect as moving it forward, so there isn't much to be gained here by doing that.


I wanted the rig dimensions to do the following...

I - Deck to mast head - 43'
J - Mast to bow - 12'
So the luff length of your jib is SqrRoot ( 43^2+12^2) = 44.6'
If you add a 5' pole it is 46.24

Now go to North Sails Direct for their prepackaged chutes. With those luff dimensions you are looking at....

44.6 - model 42
46.24 - model 46

Model..sqft.....luff......leech......foot......pri ce
42'.....710......42'......39.0'......20.4'.....$13 65
46'.....850......46'......43.7'......22.1'.....$15 70

These are a little larger than what I had assumed. I would also recommend pricing out a tri radial from other lofts. North Direct has pretty good prices, but others lofts are also doing prepackaged sails any may have a better cut for you.

[natew]

Being a totally visual type person i've kind of drawn out what I think here, does that look about right?

I don't have a good place to attach the tackline, I do have a some extra holes on the foreward chainplate which I could easily attach a block to but they are all inside of the genoa attachment. Would that be sufficient? I understand that at some point there may be something to gain by adding a bowsprit pole or something in the future.

My list of parts besides the sail seems to be as follows:
Turning Block for tackline (3/8 line)
Ratchet Block for sheets x2 (7/16 line)
T-track slide with ring x 2
Halyard Block (3/8 Line)

125ft 3/8 Sta-Set line for Halyard + halyard hardware
35ft 3/8 sta-set line for tackline + hardware

2 Eyelets on deck for running tackline (same setup as roller furling line on other side)

Missing anything?

[Stumble]

Other than discussing line selection you got it.

It is possible to fly an asym from inside the forestay but there are real issues with it.

1) there is no way to jibe the spinnaker, you have to drop it, move the haylard onto the other side of the forestay and then rehoist.
2) an asym is not cut flat at the luff, it is designed with a shoulder that projects to windward of the centerline. This shoulder is prone to major chaff where it crosses over the forestay.

If at all possible find something forward of the stay that you can attach something to, even if just by a few inches.

[cwyckham]

Yes, the tack needs to be forward of the forestay. You don't really need to run the track line back to far. I just bring it back to my docking cleat. It isn't a line you really need to adjust much.

Very nice to bring it back to a winch, but that is a nice to have that you can add later.

[natew]

Ok so then after doing some more thinking, looking and research I think i'm going to add on a Selden retractable bowsprit. That will get me my tack line out infront of the bow. But how would that effect sail sizing? I'm looking at I think the 7.5ft pole.

Also wondering the thoughts on line selection for all this? is 3/8 sta set for tack and halyard and 7/16 for sheets too much or too little?

[Stumble]

Take a look at http://www.seldenmast.com/files/exce...-E-160-162.pdf the maximum unsupported leingth is the additional projection you will get. It varies a bit with the displacement of the boat, but for a multi-hull I would contact Selden and ask for their guidance, you will probably need to shorten it a little due to the extra RM of your boat compared to a monohull of the same dimensions.

I would guess you are looking at an extra 3-4 foot of projection which means your luff will be a bit bigger, and your foot will be 3-4 longer. This of course is for your ideal sail, the one you buy will vary according to what is on the market.


The tack line needs to be picked based on the size that the pole is suited for. I don't have the spec sheet for the poles, so I can't comment.

7/16" for a spin sheet is a massive amount of over kill. The sheet load calculations could be run, but I would probably go with 5/16 tapered endurabraid. It's a lot stronger than sta-set, lighter, doesn't absorb water, and when you taper it you only buy 2/3 as much so it works out to close to the same price.

[cwyckham]

Get the lightest sheets you can still grab easily in the hand. In light wind, you don't want heavy sheets pulling the clew down. In heavy wind you won't have a spinnaker up

[Terra Nova]

Originally Posted by natew

Ok so then after doing some more thinking, looking and research I think i'm going to add on a Selden retractable bowsprit...

Oh man, you don't need that.

[natew]

Originally Posted by Terra Nova

Oh man, you don't need that.

Open to other ideas..


Its just that I have nothing forward of my headstay/roller furling to attach to. I will get a picture at some point but my forward chain plate curves around the very very pointy end of the bow and has a small plate extending upwards that is the attachment point for the headstay. Short of having another chainplate fabricated for the bow I really don't have anything to attach to up there outside the roller furling. There is potentially the anchor roller I could attach it to but that seems a little bit of a hack job if you ask me.

[natew]

So I went with a tape measure today and measured everything more precisely.. Came up with some interesting numbers.

My I measurement is 41' BUT my J measurement is 16'..

That seems to skew my spinnaker size requirements by quite a significant amount. My the equation given I need a LUff of 41ft with a foot of around 32ft... Can't seem to find ANY premade sails that even come close to that.

HMM

I measured the J measurement twice too just to be sure.

[natew]

Ok, well off we go!

I have things mostly figured out here.

Ordered a custom sized sail kit from sailrite (43x40x27) since I couldn't find anything that seemed to fit correctly. Also managed to convince my wife to sew it together too, haven't seen her so excited about something in a while!

Picked up the rigging yesterday. Went with 3/8 endura braid for the halyard and tack line and 7/16 sta-set for the sheets. Picked up two eye slides and two ratchet blocks for the sheets along with two additional blocks for the tack line and halyard. And the boat already has a mast base block and two open clutches to use for the halyard and the tack line so i'm pleased about that.

As for tack attachment... No pole, ruled that out for maintenance reasons, cost and deck clutter. Instead I found a perfect solution thanks to google images... Saw a picture of another boat (catalina 34 I think) that used a D-ring to provide an attachment point just forward of the forestay by putting the pin through one of the chainplate holes just behind the forestay and using the D shape of the D ring to go around the attachment for the stay. Well I tried every D-ring in existance and nothing would fit so i'm off today to talk with a fabricator and get one custom made, but in the end it should work great I think and won't be too expensive (ok, $100 for basically a D-ring is expensive but this is a boat we're talking about!)

PS... Spent quite a bit more than budgeted but oh well!