Mark Pearse
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Everything posted by Mark Pearse
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Hi Steven on the hatch, it sounds like the lower sole to deck height is less than the rowers' height, so at the bottom of the ladder it might be a good idea to allow enough room for a person to be able to stand & have their head through. If the ladder angle is 30-40º from vertical for the 1.5m or so of height, & the horizontal length of the hatch opening would need maybe another 300mm beyond the foot of the ladder...without doing a drawing I'd guess at 1-1.2m long. Hope this helps. edit: Just saw the 'fittings the oars' comment...if that wasn't required to be done very often, perhaps a removable panel to extend the aperture beyond what would be required for people. Mark -
that's looking fantastic, a really striking looking vessel indeed for the head height down below, what height of person are you assuming?
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Hi John it's a lovely model, it's wonderful how each stage of a build has it's own pleasures. Wishes for your good health. Mark
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Some details on the rigging done recently. The throat halyard & gaff jaws: Peak halyard setup, gaff bridle & the sliding thing. For this size of boat a 1:1 peak halyard is fine. The running backstays here are temporarily done as thread (Guttermans top stitch), but I think I'll make the main part in wire with the tackles in rope. gaff bridle is swaged: Plus some pad eyes that will be mounted on the quarters, they would take blocks for the spinnaker brace & sheets, still a bit of cleaning up to do. The tails below the pads are to increase the glued strength.
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Hi Michael, the result on the vents is very good, & I've learned something new from this. On the companionway top colour: I feel that having a different colour to the top (from the sides colour) lowers the apparent height of the overall structure, which in most cases looks better on a boat as it elongates the overall lines. I also feel that a paler colour makes it look a bit wider than with a darker colour, so again I feel that it looks better. Mark
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I made the traveller rail, starting with the small parts because they needed to be on the bar when it was fabricated due to the bends. Below is the sliding piece that the main sheet connects to - tube with wire bent & soldered. As a form for bending I held a thinner piece of wire next to the tube to wrap the wire around both to get the shape. Below are the flanges that sit on the deck - 1/4" rod drilled down the centre & cut off. The thin rod was made to fit the hole tightly by some end tapping, to help in cleaning them up. All the small pieces plus a sketch: The bending jig for the bar: The small pieces were soldered on, & then the rod bent: Then feet soldered on & the piece has been dry fitted. Not glued until I'm sure the deck doesn't need painting again. I put a gentle curve into the top bar, it looks nice & it seems that I didn't quite get enough clearance to the tiller - a bit of tiller reshaping helped also. I find that things tend to look better on boats if there are gently curves & slight angles, even if you think it should be square.
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thanks all, having the spars made I wasn't really confident that they looked right, I had difficulty seeing if the sizes looked about right or not, so I made some paper sails. It was a lot of fun & it also confirmed that the sail & spar sizes are quite good. To my eye the sails look just slightly conservative in area, but I would prefer that than if they looked a little oversized - this boats look chunky but I believe it would be lightly built & lightly ballasted. The headsail is intended to be a #2 & is still a little too large, probably move the clew forwards by 15 or 20mm & up about 10mm. I'm starting to think whether it's better for the sails to be set to appear as if they have wind, or just hang..... I'll post some photos of the rigging details shortly, Mark
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Hi Michael, I hope this signifies your plans to restart this model. I'm not so keen on the port side belaying because with water & load it might lock up. I don't mind the starboard one because, despite the mess, it will release easily. Mark
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Hi Dick, there might need to be some extra strengthening, but I think you are underestimating the strength of the planks & the way they would transfer loads from forwards to the whole hull. Mark
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Hi Steven getting ever more interesting... Do you know if the spurs were designed to break away at all?
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thanks, & on consideration Michael I have to agree with you that visually the heads are too bulbous to get away with. For this model there's a number of things that are simplified technically but I'll have a look at this one & see what I can do. I bought some packs of brass miniature rivets & I like them so much they are appearing all over the place. Mark
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I've made the gaff jaws & gaff spar, but not done the final finishing & assembly yet. The jaws are what I am guessing would have been modern at the time of the yacht design, the mid 1960's. The part that would once have been a timber jaws piece is here a curved piece of metal, probably 6mm aluminium sheet or similar with cleats welded to the aft face, & the mast face clad in leather - which I probably won't try to replicate to scale. This photo shows it approximately in its working angle - mocked up with a scrape dowel to replace the mast. The gaff angle in Australia seems to have been usually a high peak & the gaff spar length was usually almost as long as the boom. The angle means that the resolution of the parts is a bit tighter to fit in.
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Hi Goetzi the stand is beautiful. Could you say what you did to weather the timber? thanks Mark
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HI Steven I have one comment & one question: The spar wouldn't be particularly heavy but the sail would be very heavy, but considering the ready labour on board I reckon they'd be ok about a 1:1 halyard with half a dozen hefty Mediterranean types. There's also the mechanical advantage you get by 'sweating' the halyard, where you lock the tail of the halyard (usually around a cleat) & then above the locked point you pull the halyard horizontally away from the mast (it has a leverage action) - which pulls the halyard up a little bit - & then you quickly take up that slack on the downhaul part, & it inches upwards. Sorry if that's not clear. How would a double sheave in the mast actually work to get greater than 1:1? Mark
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Bravo! And thank you for patiently showing the methods used Michael, Mark
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- albertic
- ocean liner
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I actually like the slight wobbles in the beam shelf, it looks ... old
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I fitted the running backstays chainplates, after avoiding them for some time because two thin & shaped timber pieces were required, which were tricky to get accurate. But done now, as below. This will require a tackle system for the backstays so that the resultant loading on the chainplates is more or less vertical, rather than pulling them off - which would be the case if the backstays were 1:1. The angle between the backstay to the mast & the tail to the winch is such that if you bisect it (1:1 backstay), the angle would be pulling the chainplates aft by quite a lot. Likewise, they lean inboard to the same angle as the run of the backstays to the top of the mast. before: after: I have also done a mast track for the mainsail. A yacht rigged in the mid-late 1960s would have had a track for the luff, which I replicated using an off the shelf brass C channel. It's oversized for tracks of the time, but doesn't look wrong & there seems to be only limited sizes available for the C section in brass. The gap at the top to the spreaders is because the gaff throat would sit just above the top of the track when there was a reef in the main. thanks, Mark
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We changed the rig on our boat, partly to lower the CoE. Without calculating it I would guess it was lowered between 5 & 10%, & the difference was noticeable. 30% higher would be a large difference, & if my geometry/physics is good, the same force higher up would have more effect on a hull because of it's distance from the pivot point. What are your thoughts on the role of the sails on these vessels - were they a pleasant respite from the oars or the preferred way of getting around?
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Hi Steven is the CoE for the 2 sail rig much lower than the single sail rig? The single sail looks to be significantly taller.
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Very interesting. Also noted is the quite large lateen sails on hulls that don't look to have much righting moment - or even freeboard - & the wind isn't light (black & white photos at the start). On the rig balance question, I would have thought it's adjustable by changing the spar angle. More horizontal & there is more sail forward, more vertical & the sail is further aft. It would mean multiple sheeting positions so the sail could set well at a range of spar angles, perhaps a line of cleats or pegs along the rail.
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thanks Steven. Have you seen this video of a replica longship at sea? No doubt there are differences, but the hull righting moments might be similar to your craft. The incredible work done in Denmark & Norway on these craft have shown we previously greatly underestimated their abilities, & I might add the hulls seem much stiffer to heel than I would have guessed. A low square sail would be somewhat comparable to low triangular sails. Hope it helps. all the best, Mark
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Hi Steven the setup you've drawn would allow disassembly - the fixing block could be removed by a hefty thwack from the side. I am guessing that with the loads & movement of the boat, the difficulty is having a mast step that is both strong & also reliably easy to take down.
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Frank, thanks for the enjoyable & informative posts - a great model to watch come together. That's a really thin boom for the length, but obviously it works Mark
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