Subject: Re: [harryproa] Re: Charter proa deckplan question
From: "Rob Denney" <>
Date: 5/27/2008, 9:24 PM

> Can easily see 3m, and can just see 2.5m but it took me a while to
> work out 2m. 2.5m is less effort

Until you have to go through a 2.3m gap! ;-) Depends how far and how
often you are using it. We towed El (2.5m) from Coffs to Perth
(5,000 kms) in 5 days, without any problems. I take it 5 ms through
suburbia to go for a sail and regularly have to go slowly to make sure
it fits.
>> The lee hull bury only needs to be 10%, both for the mast and the beams.
> I would have thought 18% would reduce the vertical compression, but I
> suppose this is only a small area of reinforcement needed. I thought
> it would also make it easier to resist the racking loads and allow a
> bit more to play with in hatch size
All true, but the loads are manageable until it gets less than 10%.

>> A double ballestron is a lot of work, cat schooners with self vanging
>> booms are a much better bet, sheet loads are low, and reefing is
>> easier.
> If the sheeting is low enough, then I wouldn't bother

It is the equivalent of a traveller control, without the friction of
the car on the track.
>> Any time you have steering trouble with one rudder (light air is more
>> likely than heavy in my experience) lower the front rudder as well.
>> The boat will steer as if it is on rails. We sailed El in 10 knots
>> breeze with 2 adults and 3 kids (250 kgs all up) with one sail and one
>> rudder. Shunting and control were no problem, although it worked
>> better with the fatties sitting on the rear beam. Pretty wet ride,
>> though as there was not much beam clearance with all of us sitting on
>> the ww hull.
> That is good to hear. In light airs, I would expect the front rudder
> to be needed a little as the bow has less sideways resistance.
> I still prefer your squeeze and lean-on method over a mould for the
> hull bow shape. I was just trying to avert as much hand glassing as
> possible and it seemed easier to fair a single cut and shut rather
> than half a dozen
> For the top half of a wingmast, I've been thinking that basalt fibre
> may be good enough as you are wanting more flexibility and it is a
> wider section.

True, but when you ask the sailmaker the minimum desirable flex the
answer is always, zero.
> I was also wondering about making hatches using basalt cloth and some
> carbon tow for the frames. My son is pretty good at making moulds and
> thought it might be possible to make some moulds to make a nicely
> finished job. It would be only slightly thicker than aluminium but
> would be a bit lighter and when considering 8-10 hatches it may be
> worth the effort. Have to check the thickness of the polycarbonate needed.

Go for it! I will have half a dozen, once you have the system sorted.

>> regards,
>> Rob
>> On Mon, May 26, 2008 at 8:26 PM, Robert <cateran1949@...> wrote:
>> > -For the top sides, a simple conic section with radiused edges would
>> > surely be easier than strip plank. I checked out the pre glassed
>> > poplyprop panels and they were a very reasonable price. Not that
>> > different from what I could buy the materials for, let alone all the
>> > hassles and the vacuum bagging disposables.
>> > My idea for the bottom of the hulls is to have some 20' panels,
>> > preglassed one side. glass to above the bilges, glass the middle
>> > section together and then do some cutting at the keel and the bilges
>> > to make the bow. It would go from round bilge gradually to a chine. I
>> > don't think a chine would be bad near the bows as it would further
>> > damp any pitching. If you wanted to, you could round these chines by
>> > putting in some creases in the polyprop on the inside close to the
>> > join All but the chine , the keel and the joins between the 20'sheets
>> > would be fair.. If you wanted to , you could z jion the sheets such as
>> > used with balsa panels
>> > To join the bottom to the sides I was thinking of a stepped hull such
>> > as Todd's model, only instead of a wide step, I would break it into
>> > two steps. This can be done with a one sided glassed zig zag panel
>> > made on the table separately, and having a bit of a concertina effect
>> > to allow easier tolerances in the joining. After the joining , it can
>> > then have its other side glassed and thus stiffened up. Joining the
>> > deck or cabin roof to the sides, I would use a KSS method to make the
>> > deck and topsides down to the bottom of the portholes, only having the
>> > port holes where the cuts are , thus significantly reducing the
>> > fairing, especially with a sponson to cover the joins. On the inside I
>> > would have a big bevel with hatch large enough to slip through. It
>> > would provide ventilation, a lovely view of the fishes, and a chance
>> > for the galley slave to catch the fish of the day and to reduce the
>> > time from the water to the frying pan. The extra width down below
>> > allows an area for someone to get away and catch up with their
> writing.
>> > The sleeping set up has me vacillating, as I am tossing around whether
>> > to make it easily trailable with telescoping beams to reduce it to
>> > 3m-permitted in daylight hours with a wide load sign. or 3.5 m
>> > -permitted with wide load sign and flashing lights. I was considering
>> > flaring out the lw hull to 1.2m to give more bury for the crossbeams
>> > and also to make a couple of cozy doubles in the lw hull. With the
>> > flare out to 1.2m in the ww hull, leaves 1.3m wide shelf berth in the
>> > ww hull. The other possibility is to have have the berths in the ww
>> > hull stretch across the boat by having a slide out foot locker with a
>> > neoprene flange to make it watertight. This allows a large saloon and
>> > steering station at deck level or smaller saloon and narrower
> trailing.
>> > Still torn between the simplicity of the single Ballestrom rig and
>> > having a schooner rig for control in skinny water.-possible even a
>> > double ballestrom rig to reduce sheet loads. This would allow the
>> > booms to be a bit lower as there wouldn't be such interference with
>> > the cabins and possibly close the gap between the sails and the top of
>> > the lw hull, thus improving efficiency.
>> > There is one small niggling doubt about the beam hung rudders. Clearly
>> > they work and are far back enough as the single cat rigged Elementarry
>> > with the single rudder forward of the beam performed OK, but my
>> > thoughts are for when you are going to ww in thirty knots, there is
>> > messy water causing increased resistance, reefed down to the main and
>> > the ww hull is loaded to the maximum, will it still be far enough
>> > back. It would be interesting to see El perform with an extra 200kg in
>> > the ww hull. I suppose in the case of reefing the ballestrom rig, you
>> > could reef by reducing the area of the main and leave the jib, or reef
>> > the main further and remove the jib. This is a case for a roller
>> > reefing jib. You could also make sure the crossbeams are as wide apart
>> > as possible.
>> > With deck mountings on the lw hull, you could have the beams wider
>> > apart at the lw hull
>> >
>> >

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