Mast-head spinnaker for h30?

[Scott19770]

I have a '93 H30T - a fractional rigged boat. I have been looking for an ASYM that is bigger than what I currently have and had a lengthy discussion with one of the local sail lofts on this subject.

I was a bit surprised when the question "what about a mast head rigged ASYM?" - my answer was "I don't know". The boat was designed to be fractionally rigged, but what issues might I encounter if I went with a mast head rigged ASYM?

My use model is river sailing/racing - the latter being the reason for exploring a larger ASYM. I would not use the ASYM in more than 20K apparent, but I know a mast head ASYM would be putting stress on the mast section above the top stays, in addition to the forces already present from the main. The safe way is, of course, to go with the fractional rig ASYM - but the extra sail area is very tempting.

The question: Has anyone seen, or do you know of fractionally rigged boats flying mast head ASYMs. Hear of any pros or cons?

Thanks in advance for any insight you might have on this topic.

 

[Jackdaw]

You called it exactly right. Flying a spinnaker masthead on a fractional boat places pressure on an unsupported section of the mast. Is this OK? It depends.

Some boats do this by design. The Beneteau First 35 is good example. The 7/8 rig is designed and spec'ed for it.

Some boats do this as a mod. My First 36.7 flies fract kites as a class, but some owners in light air venues take a rating hit to fly masthead sails. Its an easy mods on the 367 because the halyard is already masthead.

Should you? Depends. Your boat is 3/4 fractional, and that means a lot more unsupported spar vs a modern 7/8 fract. I'd worry about it on a breezy reach, the exact weather that best suits that asym sail. 20 knots apparent is a ton of breeze downwind. In light air it might pay off. In a breeze it will not. Remember you carry the ratings hit upwind and down, but will only benefit on light downwinds. I personally would only do it if I was losing lots of close races on light air days. Your boat SHOULD sail to its current rating now. This will change its nature. You're doing only because you can find a good deal on a used sail? Personally I'd pass. But depending on your typical wind, it might pay off!

 

[Scott19770]

Thank you Jackdaw, for confirming my concerns. I think for now I'll stick w/current fractional designed asym.
Fair winds,
~ Scott