Hans-Erik, that is the hard part.

To find the scantlings of a mast, one can approach it from two angles.

Either do as in Chapter 6b of TCPJR and start with guessing on the boat’s ultimate righting moment:
With a displacement of 9250kg and with 3300kg ballast, I would guess the righting arm to be 1/5 of the beam of vessel (3.54m).

The ultimate righting moment, should then be
Mr = 9250kg x 3.54m x 0.20 = 6549kpm.

If we choose the mast strength to be 2.5 times Mr, the mast must take 16373kpm.Then one can produce a mast  in any material with this strength in mind.

This method doesn’t count with sail area or LAP, but as long as the LAP is not extreme, I think we get away with it. A very tall mast will suffer quite some additional loads due to pitching, but this factor is hard to quantify. That's why we have safety factors...

The other approach to find a wooden mast, is to go to Chapter 6 and use my modified Hasler-McLeod method. This would result in a hollow spruce mast with 34cm diameter (check it, yourself). Since Finland is full of spruce trees, that could be an affordable alternative.

On such a big steel (?) vessel, a steel tube mast could be an alternative, but that is outside my area of experience. I hope Paul Thompson could help us there.

Arne

Good, Eero.
Then I guess I would suggest one of the two last rigs I have presented.
The light winds in the Bay of Finland during summer, speaks for the last one; the one with AR= 2.40 and SA= 65.6sqm.
However, we don’t get younger as the years go by, and the shorter 13.4m mast is cheaper and easier to deal with than the one at 14.9m...

As for performance; even the smallest JR will outperform the masthead Bermuda rig on the downwind leg. Close-hauled, I guess I would put my money on the BR, in light winds.

The only ‘hard’ job when sailing with a JR, is hoisting the sail. On your boat, that can easily be overcome with an electric capstan. Some of these are meant for hauling up the anchor, and are not terribly expensive. Hoisting the sail from bottom to top will drain a 12V battery with less than an Ampère-hour.

Anyway, rigging the boat with two sticks will cost a lot more  -  I would say, forget that.

When organising the sheet, it is important to give them a good layout to make them easy to haul at by hand and via manual winches.

Arne

PS: I have sent the drawing in QCAD (.DXF format) to David, to let him suggest a rig. If others will have a go, and can handle that format, just let me know.

PPS: In case the mast position I have suggested results in awkward access to the fore-peak, the mast may well be moved 10-15cm forward, and it can even be offset 10-15cm to one side, without suffering any handling problems.

Good, Arne. I like the reasoning, and I like the end result.

Except for the missing forward rake ...

Eero,
I realise that I jumped into drawing mode too early. Before presenting any sketches, I should have asked a few questions (I see now that you have hinted about it in your profile):

• ·         Where on a scale from 0-100 do you regard yourself to be (0 = motorboatman, 100 = die-hard pure sailor)? How much do you focus on sailing itself?
• ·         What waters will be your preferred to sail in for the next five years?
• ·         How many people will you be on board, mostly?
• ·         How big SA do you actually make use of today, with the original rig?
• ·         How is the helm balance with the original rig?

I will not argue for or against any rig or sail area until I learn more about your needs.

However, just for fun, I have now added a ‘minimum rig’ of 57sqm (same mast position and CE). This would result in a SA/Disp.=13.2. See below.

As for rudder incorporated in the CLR or not, I generally avoid that, in particular with sloop rigs. I try to end up with about neutral helm when close-hauled in light winds, and keep the rudder ‘as a spare’ for controlling the boat on a beam-to-broad reach in rising winds.

Arne

There is another possibility if you want a sloop rig with the mast a little further aft, and that is to consider a SJR, which typically has higher balance.

Here is one of Slieve's SJR sails superimposed over Arne's Johanna sail, with the geomtric centre lines of the two sails in the same position.

As you can see, this puts the mast centre line somewhat further aft.

In the current "Featured Boat" you can read that Pete H. put an aerojunk rig on Blossom to solve an accommodation problem in much the same way.

When placing a SJR sail plan, people have found that the geometric centre line of the SJR (near enough to a vertical line through the mid point of the boom) can coincide with the geometric centre line (through the so-called "centre of effort") of the original bermudan rig. This makes use of an assumption that the original bermudan rig is in the right place with regard to under water profile, rudder etc.

The above drawing will be pretty close to that).

I am not sure if this helps. Also not sure if a single sail as large as that is a practical proposition !) but if you want a sloop, it is another possibility to consider.