HI Herb,
Take your point about the rudders. See previous post by rob about not getting too close as the water can interfere with the lw hull.
For me, I have a sleeve going from the edge of the bride deck to the ww edge of the ww hull and the beams penetrate this sleeve 700mm when fully extended and go right to the other end when fully telescoped. There is a full bulkhead that the sleeve attaches to that also supports the cabin floor and transfers the lift from the beam to the rest of the hull. There will be a thin hard shelf to walk along to lw of the cabin but that is level with the bottom of the beam rather than the bridge deck. Near the fore/aft centre at the cockpit I will have a step down. I haven't yet worked out the full connections for this shelf that doesn't interfere with the ability to telescope the beams.
If you are having fixed beams, there is nothing stopping having lugs under the beams to support stringers under the shelf
I can understand wanting to have low beams for access. Better to have a fold down ladder than drag beams through the water I will probably have a ramp, though lighter and skinnier than 'Rare Bird's'.
The sheet needs to be attached well to ww to avoid the problems of being caught aback. If sheeted well to windward the rig will weather cock in the case of an accidental gybe. Otherwise there is the risk of capsizing to ww as the sail will fill on the opposite side and the lee hull is much lighter than the ww. This doesn't preclude the purchase being at the beam positions on the ww hull, but no further to lw. This is one of the big safety features of the design and distinguishes them from most other proas.
Fair enough about the actual waterline being a lot less than the hull width. I don't understand well enough the effects of waves moving along the hull, whether it cause significantly more drag or is balanced a bit by lift. Yours is much simpler than my flared sides.
--- In harryproa@yahoogrou
>
> Hi Robert,
>
> Thank you for the comments. I have been thinking about them and have the following:
>
> Rudder position
> It is not clear to me why the position of the rudders inwards is at all material. If you position a rudder as close as possible to the lee hull as possible and still allow 30 degree rotation towards the hull the distance from the hull will be cosine(30)*chord*
>
> Beams
> I take your and Rudolf's point about keeping beams away from the sea. I hadn't thought this through. It will be easy to move the lw end of the beams in a bit and raise the bottom of them them to bridgedeck level. However, I am a bit concerned about raising them above the bridgedeck, because then I don't see how the deck and netting will have a strong attachment point, assuming the deck and netting are at the same level as the bridgedeck.
>
> I wanted to keep the deck/netting at the same level as the bridgedeck to avoid hitting my head when entering or exiting the saloon. But there is no particular reason the deck/netting couldn't be raised. Another consideration is that I want to keep the beams reasonably low to avoid climbing high ladders when entering a dinghy, which I assume will be next to a beam rather than over the lee hull.
>
> Sheeting
> I don't understand why the sheet needs to be attached to the cockpit. Consider the case on a run where the sail is 90 degrees out to the side - then the sheet will have no leverage at all. I had thought the sheet attachment needed to be at least as far from the center line as the attachment on the boom. One obvious place is directly under the end of the boom on the lee hull. I was concerned about having to reinforce the lee hull when there was a beam available and not being able to oversheet, so decided to attach it to the beam instead. However this has the potential disadvantage of chafe on the lee hull when the sheet is eased.
>
> Hull width
> Actually the wl beam of the ww hull will be considerably narrower than 1.1m - I think about .7m (although I need to redo those calculations as they were based on an earlier version with different parameters), which would give a length to wl beam ratio of 13-14 at max gross weight of 2.5 tons assuming 2/3 of weight is in the ww hull. So I think we actually agree here.
>
> I think the only practical difference between us here is that you are keeping a 1/2 circle to a ledge which acts as a spray rail, but I am using a larger radius, which gives more strength and easier building at the cost of slightly increased wetted surface area. I am happy with this trade-off as I think it is mostly relevant in very light air when it is easy to add sail area - or start the motor:-(.
>
> Best regards
> Herb
>
>
> --- In harryproa@yahoogrou
> >
> > Hi Herb,
> > Some points I have considered when preparing to build my Harry.
> > I agree very much with what Rudolf says about clearance. I am going for 600mm clearance for the bridgedeck, with even less in the saloon /cockpit area and a full 1m clearance of the crossbeams at the lw end when resting. This reduction in clearace in the cockpit saloon allows a lower roof to the saloon and less windage. As the bow depressses when sailing this decreases significantly. I am constrained to under 15m lw hull as after that regulations become a licorice allsorts of trouble.
> > At full drive with full load, the bows are expected to depress to about 850mm, leaving about 50mm above water. This leaves the transom just abot to lift clear and the ww hull pretty light on the water. This leaves 600mm clearance for the front beam in flat water. 600mm is not much in the way of waves. You are going with four foot shorter bows.
> >
> > The wave resistance very quickly comes into play with these boats so this is why I am going with about a 14:1 ratio at 680mm with 400 fully loaded draught at rest for the ww hull with a flare above to deflect some of the spray.I am going slightly finer ratio for the lw hull at 900mm
> >
> > I will be having the rudders on a mini beam set in a slight flare on the edge of the lw hullat 4.6m from the centreline. This is not so much for trying to get them closer to the ends but to allow a kick up system and clear beams. I want to keep the beams clear as it is to be able to be telescoped to 4.2m(42 decametres) (I have read the many books of the trilogy and sometimes the exercise seems like needing an improbability drive)
> >
> > About the fore aft stability, the loads are generally regarded to be less than the loads on the beams holding a ww hull up in the air in bouncy seas, so if the beams are a box section with a carbon rod in each corner then all that is needed is to make the top and bottom panels the same as the side panels.
> >
> > The sheets need to be taken to the cockpit directly to prevent being taken aback.
> > I think this just about eliminates the need to drag those crossbeams through the water;<)
> >
> > I personally cannot see why the rudders need to turn 360. If hove to, then hopefully the ww hull will stay to ww and the rudders can simply lie at right angle. I would prefer to lift them and hang out a drogue on a bridle and have the bows to the seas.
> >
> >
> >
> > Sangduen is a beautiful name. Look forward to seeing them on the water.
> >
> > regards
> > Robert
> >
> > --- In harryproa@yahoogrou
> > >
> > >
> > >
> > >
> > > Hi Robert,
> > >
> > > Thanks for the comments. Here are some of my considerations, which will one date go in the file as notes.
> > >
> > > I did some thinking about the wide ww hull and decided that it has the advantages of providing a sort of spray rail and reducing increased draft with increased load. I expect the boat to be overloaded more often than underloaded. It does have the disadvantage of increased wetted surface, but I calculated the increase as about 4-5% compared to a perfect half circle at typical designed load. I felt this was a good tradeoff because the increased wetted suface could be overcome by incrased light air sail area (perhaps about 10% increase in drifter size assuming it is about equal in size to working sail area).
> > >
> > > Actually the rudders are about as close to the lee hull as I can get them (.4m) and still have complete circular swinging room assuming .5m chord. I am perfectly happy to move them closer if it can be done. I decided on circular swinging room so I could put the rudders in any position when lying ahull or hove to in a storm.
> > >
> > > The main beam strains are intended to be taken by the central beams. The fore and aft beams are there only to hold the rudders, provide sheet attachment and stabilise the ww and lw hulls. That is why the fore and aft beams are splayed, to maximize the hull stability and get the rudders as far aft as possilbe. Given Rudolf's recent experience this may have been a good idea.
> > >
> > > The 42 foot length on the lw hull is actually just a joke based on Douglas Adams' books (e.g., So long and thanks for all the fish). Hence the type name Answerharry. I am also tempting fate by naming the boat after my wife - Sangduen (it translates as roughly as Moonbeam).
> > >
> > > Best regards
> > > Herb
> > >
> > > --- In harryproa@yahoogrou
> > > >
> > > >
> > > > Hi Herb,
> > > > It looks pretty good to me. I am not sure about the width of the ww hull. I am going skinnier and deeper (700mm wide and 350-400 deep) but Farrier reckons his wider centre hulls go just as well or even better so I can't say that it is a bad idea going that wide. I am also going longer (50') but can understand constraints on length. I would have thought that 40' would have been a more frequent constraint. I like the idea of a splayed mast system with the attached rudders, though I would go as close to the lw hull as possible with the rudders, but it does lead to constraints on how the beams are attached
> > > > I also hope the telescoping mast works.
> > > >
> > > >
> > > > --- In harryproa@yahoogrou
> > > > >
> > > > >
> > > > >
> > > > > Thanks Rob,
> > > > >
> > > > > I am some time off from committing to anything at the moment. Still don't have a shed built.
> > > > >
> > > > > At the moment I am more interested in feedback on the layout, beams, rudders, etc. than the rig.
> > > > >
> > > > > I think it would be quite easy to subsititute an easyrig for the telescoping mast as the first version I drew had the easyrig. However, the more I think about the telescoping mast the more attractive it seems, so I really hope you don't find it is a disaster:)
> > > > >
> > > > > Thanks for your (and everyone's) help.
> > > > >
> > > > > Best regards
> > > > > Herb
> > > > >
> > > > > --- In harryproa@yahoogrou
> > > > > >
> > > > > > Looks really good. However, I suggest you wait until we have some rig
> > > > > > results before you commit. Should not be too long to wait, panel production
> > > > > > for Solitarry has started.
> > > > > >
> > > > > > regards,
> > > > > >
> > > > > > Rob
> > > > > >
> > > > > > On Mon, Oct 12, 2009 at 10:03 AM, squirebug <squirebug@> wrote:
> > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > Hi Gardner,
> > > > > > >
> > > > > > > I have uploaded a pdf version.
> > > > > > >
> > > > > > > Best regards
> > > > > > > Herb
> > > > > > >
> > > > > > > --- In harryproa@yahoogrou
> > > > > > > Gardner Pomper <gardner@> wrote:
> > > > > > > >
> > > > > > > > Hi,
> > > > > > > > Is it possible for you to put it up as a PDF or image file of some sort.
> > > > > > > I
> > > > > > > > am definitely interested in looking at it, but I don't want to install
> > > > > > > > OpenOffice on my mac just for this one thing.
> > > > > > > >
> > > > > > > > - Gardner
> > > > > > > >
> > > > > > > > On Fri, Oct 9, 2009 at 7:24 AM, squirebug <squirebug@> wrote:
> > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > This is a preliminary design for a cruiser I might start building next
> > > > > > > > > year. Any and all comments/criticisms welcome.
> > > > > > > > >
> > > > > > > > > It is rendered in odg format, which theoretically is readable by newer
> > > > > > > > > versions of microsoft, but it is probably much easier to download
> > > > > > > openoffice
> > > > > > > > > for free from www.openoffice.
> > > > > > > > >
> > > > > > > > > Best regards
> > > > > > > > > Herb
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > --- In harryproa@yahoogrou
> > > > > > > 40yahoogroups.
> > > > > > > > > harryproa@yahoogrou
> > > > > > > 40yahoogroups.
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > Hello,
> > > > > > > > > >
> > > > > > > > > > This email message is a notification to let you know that
> > > > > > > > > > a file has been uploaded to the Files area of the harryproa
> > > > > > > > > > group.
> > > > > > > > > >
> > > > > > > > > > File : /Answerharry/
> > > > > > > > > > Uploaded by : squirebug <squirebug@>
> > > > > > > > > > Description : Cruiser for a couple.
> > > > > > > > > >
> > > > > > > > > > You can access this file at the URL:
> > > > > > > > > >
> > > > > > > > >
> > > > > > > http://au.groups.
> > > > > > > > > >
> > > > > > > > > > To learn more about file sharing for your group, please visit:
> > > > > > > > > >
> > > > > > > > >
> > > > > > > http://help.
> > > > > > > > > >
> > > > > > > > > > Regards,
> > > > > > > > > >
> > > > > > > > > > squirebug <squirebug@>
> > > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>
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