Time has passed and autumn has arrived, so the work on the hull and mast has to be put on hold, and there will be time to look into sail and battens. I have put together the mast and had coats of epoxy on it, so it can be stored for winter. Painting will be done when it starts to get warmer again. 

The sail and battens is where I need help. I have drawn a sailplan, but I would like to be assisted on specifying sailcloth and batten sizes. Boom, yard and battens, all in aluminium alloy. Measurements are metric here, total sail area will be 14 m2. Haven't found anything specified for such small sail size here...

Best regards,

Eerik

eerik mee wrote:

Jim Hall wrote:
...But the displacement would work out a lot more than 640kg. There would need to be much more lead ballast to get the waterline in the correct place because of the extra immersed volume . The self righting ability (angle of vanishing stability) depends on there being enough ballast to help the boat stay upright and to counter the extra sail area that you'd need.

Completely agree with that, Jim

Extra weight means using a larger, more powerful car for towing. I can use a medium sized family to tow mine, but you're going to need a bigger motor.

I also have a medium size family car and it definitely would not be enough to tow her fully equipped and ballasted. I haven't thought of her as of treilering her each time, instead more like keeping her in a marina. But will consider about treilering later...

If you move the mast forward, away from the vent box, how do you intend  the water - rain and splashes - which will get in around the mast hole to drain?

The plan is to use what seems to be called mast boot. Here an example.

Jim Hall wrotThanks for your kind comment about my blog BTW.

You are welcome. It is interesting :)

Regards,

Eerik

The advantages of the 'regular' Paradox include being very quick and easy to launch as a 'trail and sail' package . Also the mast is very quick to take down for road  transport or passing under low bridges.  I can take my mast down in about 30 seconds while the boat is afloat.

This suits me fine, as I can keep the boat at home and avoid marina fees. and I'm willing to tolerate the tiny living space and limited speed in exchange for the economy and convenience   But if you're going for a bigger heavier boat that is be kept at a marina and not be towed behind your car, why limit yourself to 16ft?

I think that a greatly enlarged Paradox with a junk rig would be viable . Say, doubling the length and beam and depth would give a 27ft length with 8 times the internal volume. More speed and comfort for you, no?

Best

Jim

eerik mee wrote:

Jim Hall wrote:All fascinating to me as the user of a 'regular' paradox and I've only just returned from an eleven day jaunt in my little boat. A 20per cent bigger one makes some sense as it would give you some more living space although , now that I'm used to it, the living space in mine seems sufficient

:) Nice to hear about your trip and read it in your blog!

So Eerik , have you worked out what the displacement will be and is it within your car's towing limit?

I haven't really decided the trailering part yet. Displacement should be the same as per plans - 640kg or 1410lbs times 1.2, But the total weight - not sure yet. I will have to weigh when ready; and then decide on trailer during testing the boat. 

Is the mast going to be located in the vent box as per the original?

The mast I will move out from the vent box, just before the bulkhead 2. I make a round mast and a bit bigger, a bit longer distance between the partner and mast step; as there is some extra weight on sail + higher aspect ratio. But mainly because of the sheets: the boom and batten ends should be a bit forward from the transom (or then there has to be a set of sheets on each side).

I'm not sure what the advantage of having a junk rig is on this boat.

There is a chance that there won't be any... but a few reasons why I considered alternative rig, are that I believe cambered sail will have better windward perfomance; I'd like to reduce the boom's overhanging; junk rig is just cool and I get some satisfaction from designing/redisigning/building process as well, beside sailing.

The biggest shortcoming is that my boat is slow to tack and all too ready to get stuck in irons. I have a hunch that making the foot of the sail shorter to give a slightly higher aspect ratio would improve this...

Actually Matt has also designed a new sail with shorter foot and higher peak and prefers it to original sail; the only disadvantage he mentiones is that it doesn't furl as well...

Regards,

Eerik

As you say, the material sizes for the 'regular' Paradox would work  OK for a 20 per cent bigger version. The boat as designed is very sturdy.

But the displacement would work out a lot more than 640kg. There would need to be much more lead ballast to get the waterline in the correct place because of the extra immersed volume . The self righting ability (angle of vanishing stability) depends on there being enough ballast to help the boat stay upright and to counter the extra sail area that you'd need.

Extra weight means using a larger, more powerful car for towing. I can use a medium sized family to tow mine, but you're going to need a bigger motor.

If you move the mast forward, away from the vent box, how do you intend  the water - rain and splashes - which will get in around the mast hole to drain?

I already have the later type sail on mine which replaced a badly cut one. A bit better to windward but still a slow tacker.

Thanks for your kind comment about my blog BTW.

Best

Jim

eerik mee wrote:

Jim Hall wrote:So Eerik , have you worked out what the displacement will be and is it within your car's towing limit?

I haven't really decided the trailering part yet. Displacement should be the same as per plans - 640kg or 1410lbs times 1.2, But the total weight - not sure yet. I will have to weigh when ready; and then decide on trailer during testing the boat.

Robert Biegler wrote:

eerik mee wrote:

I had to move the mast a bit forward, to get to step it a bit lower, but also to avoid boom (and battens) to overhang the transom.

I had a Paradox, considered converting to junk rig because the existing lug rig was inefficient upwind, but decided against it.  Most of the lateral resistance comes from the rudder.  Moving the rig forward takes pressure off the rudder, just as sailing upright does, and sailing upright dramatically increases leeway.  My opinion is that you will either need a mizzen, a bow board, or something more exotic.  I considered something resembling the foils on the new Open 60s, but hinged instead of sliding out of the hull.  I would have mounted them as far forward as the mast.

All fascinating to me as the user of a 'regular' paradox and I've only just returned from an eleven day jaunt in my little boat. A 20per cent bigger one makes some sense as it would give you some more living space although , now that I'm used to it, the living space in mine seems sufficient.

So EeeriK , have you worked out what the displacement will be and is it within your car's towing limit?

Is the mast going to be located in the vent box as per the original?

Robert, with the original sail the windward performance of mine was poor but after I had Chris Scanes make up a new better shaped sail it's now much improved. Perhaps not going to win any races to windward but with a reasonably acceptable windward ability.

I'm not sure what the advantage of having a junk rig is on this boat. On my 'regular' paradox sail handling (reefing and furling) is very easy and junk rig isn't likely to give a major improvement in performance. The existing sail is like a junk but without all the battens.

I've had my boat for 6 years and have never noticed that leeway is worse when the boat is heeled less while sailing in light winds. Mind you,  the tides are strong round here and are either with me or against me and would be difficult to distinguish leeway from tide stream effect...

The biggest shortcoming is that my boat is slow to tack and all too ready to get stuck in irons. I have a hunch that making the foot of the sail shorter to give a slightly higher aspect ratio would improve this...

best

Jim