My mainsail is wimpy. How can I improve it?

[LeftyI36]

My Islander 36, which I love dearly and recently moved aboard, is a dog. The original sail plan for all I36's is, and has always been, improperly sized to the boat. The mast isn't tall enough, (P = 39.25) and the boom is too short (E = 12.75), which really hinders their performance and requires that one nearly always use the 150 Genoa in order to make any headway.

I've been looking at mains with full battens and/or with a larger roach, but today I had an epiphany; what if I were to replace the boom with a longer one? I'd have to measure, but I'd say there's 2-3 feet before the backstay would be an issue. The main sheet and traveler are cabintop, so it really wouldn't change much there, but it would allow me to design a new main that might have a lot more punch to it. My only concern would be overpowering the rig. She is over 30 years old and in excellent shape, but mostly original equipment, (kinda like my wife). Any ideas?

Thanks in advance,

Lefty

[SanderO]

You may not get much of a roach

jef
sv shiva

[Zogumwesterly]

I agree with SanderO, and have you ever noticed that beachcat mains last forever, fully battened mains are awesome in terms of durability and performance. the other thing is,I don't think it would be such a great Idea to move the center of effort that far aft. I tend to think that your pointing ability would suffer from extending your foot as well.

[sailingdog]

The SA/D of your boat is a bit on the low side, at 16.28 or so.

However, increasing the boom length and sail size will move the Center of Effort aft, as pointed above and may cause some issues with the sail/keel balance—weather/lee helm, etc.

It may also require you to increase the size of the running rigging, since the additional sail area will impose greater loads on the mainsheet, traveler, boom vang, etc. It may also present more of a risk of snapping the boom, which sounds like it is a mid-boom sheeting setup—unless you get a larger spar—since mid-boom sheeting presents higher loads on the boom than end-boom sheeting does.

Finally, adding all this weight aloft—new, longer, larger boom, larger mainsail, possibly heavier rigging, etc—will reduce the stability of the boat a bit... since the more weight aloft you have, the more tender your boat will be.

[tenuki]

why not just get a 170% genny?

What kind of sailing do you normally do?

[blt2ski]

I'm in the same position. What I noticed, is that I have an additional 3-4" on my boom to make the foot longer, along with an additional 3-4" on the mast I can go higher! Along with a full roach, this will give me an additional 30# of sail area. IE from 160 to 190! While not a lot of SA increase, still an increase of 20% over what I have! with having done nothing to the rig itself. You may be in the same position I am, talk to a sail maker to verify this!

MARTY

[TrueBlue]

The I36's boom does look a bit short - relative to the mast height.

[LWinters]

So let's take this a step further. I have a ketch which I dearly love, but the simplicity of a sloop has it's advantages. Has anyone ever heard of converting a ketch to a sloop? I am sure it would require a new spar and boom, rigging, heavier winches for the larger sails and a dozen other things I am not thinking of. Just wondering how much of a beast this would actually be?

[TrueBlue]

There's an Allied Mistress ketch across from my slip . . . just can't picture the conversion to a sloop. Have to admit though, even my boat sails past it pretty easily.

[LeftyI36]

Thanks for the great advice. Like sailingdog said it does seem like a bigger heaver sail and boom might be a little too much for the old stays and shrouds, but I gotta do something. Maybe just a little bigger sail, there is some room to go taller and longer by a couple of inches. I was even thinking maybe a square top type sail, with full battens and huge roach. I normally sail short distances, primarily long day sails once or twice a week and the occasional overnighter (out of San Diego). But I rarely go more than 100 miles off shore and I would probably never take this boat on an ocean crossing. I'm also a pretty fair weather sailor, and do what I can to avoid winds over 25 knots.