Thomas,
I guess you can choose between the sail with AR=1.89 and the one with AR = 1.93.

The one with AR = 1.89 happens to be the same master sail which Paul Schnabel used when constructing the JR for his Ilvy.

Mast:
There are two things to think about here.

First, the taper of the mast should not be a straight cone-taper. The best is if it is barrel-tapered, the way flagpoles or catrig masts are. The cone taper will make the middle of the mast a weaker area. A simpler way than using the fancy barrel taper could be to make the mast with a constant diameter up to 20% of the LAP above deck and then make a coned taper up to the mast top (43-45% diameter). The diagram should illustrate this.

Making that solid spruce mast:
I understand that you plan to shape it from a tree trunk(?).
A friend of mine did that for a 32cm gaff rig mast. He started with shaping the mast while the trunk was wet (raw). Then, before leaving it to dry, he made a cut from end to end with a circular saw. The cut went about halfway to the centre.
As the mast dried, this saw cut opened up quite a lot, saving the mast from developing cracks (splits, or whatever) in the rest of it. The owner also gave the end grain at both ends some paint, to slow down drying there. Even though he left that mast out in the sun (well, Stavanger sun, at 59° N...), protected from rain, it went well.
Finally, he evened out this saw cut with a router and then glued in a spline  -  after having installed the wiring for the top lantern. This mast has proven to last well.

Cheers,
Arne

(..full size diagram under Arne's sketches, section 3-38...)

Arne wrote:

Thomas,

your proposed JR looks promising to me. If the helm balance is good with the present rig, it should be so with that JR.

I would make a few minor changes.

• ·         Raise the whole sail a little, say 100-200mm to get better clearance above the foredeck.

Yes. The clew rises when the boat is gybed - which means that the tack drops, and is in danger of getting caught under the guardwires or pulpit [how do I know ;-)]

• ·         Ensure that the halyard drift  -  clearance between the slingpoint and the mast top  -  is sufficient. Better a bit too much than too little. My rule of thumb is to have that drift 18% of B (i.e. 1.13m, here, disregarding the yard). If you add another 20cm to the mast, you will have more room to play with to shift the sail a little forward or aft until the helm balance is just right.
• ·         I suggest you make that sail with seven panels. My main reasons for using seven panels in my sails is that the luff of each panel will be shorter, and thus stays tauter without needing any downhaul. I also find the reefing steps to be just right with seven panels.

Yes. Six sheeted points are needed on a sail this size.

If you grab the 7-panel Johanna 60 master sail with AR = 1.93 and scale it up until B = 6.30m, you will get around 60sqm sail area.

Good luck!
Arne

Good day everyone,

I am looking for thoughts and input on my ideas for converting an Island Packet 35. I'm thinking of using a sloop rig for the reasons of easier conversion, less lines, and simpler sail handling. Although I'm aware the size of the rig (60sqm) is towards the upper end of what is manageable. I would use a 60 degree yard angle with maximum balance to help mitigate sheeting and steering forces. This seems to work well with mast placement being through the v-berth hatch.

Id like to use port/starboard sheets ran to the the existing mainsheet traveler mounting points so they could easily be led back under the hard dodger and, most importantly, keep the aft end of the boat clear so I can keep the hard cockpit cover and solar panel arch. 

I have access to an old growth sitka spruce that would be suitable for making a dugout mast. An aluminum light pole would be prefered but they are few and far between where I live.

See attached pictures for reference.