Search found 65 matches
- Wed Nov 06, 2024 9:45 pm
- Forum: Hydrofoils
- Topic: Hinged Bruce foiler
- Replies: 9
- Views: 102522
Re: Hinged Bruce foiler
The attached Excel file is intended to accompany an article in Catalyst 68. It calculates heeling moment with the foil to weather, under assumptions described in that article.
- Mon Dec 04, 2023 5:54 pm
- Forum: Members Sales and Wants
- Topic: Hapas free to a good home
- Replies: 3
- Views: 78650
Re: Hapas free to a good home
I could use the Rousson design for my next project, a hapa-stablised canoe. It would make a good comparison for the design I already built (rather crudely). But for £2800, I could probably get a custom-built foil. I suppose size is the problem. Is it possible to take it apart? The next project will ...
- Sat Jul 29, 2023 12:32 pm
- Forum: Hydrofoils
- Topic: Hinged Bruce foiler
- Replies: 9
- Views: 102522
Re: Hinged Bruce foiler
I had opportunity to sail in 15 knots average wind (confirmed by checking the average wind speed recorded at Trondheim harbour weather station at the time) and a wind direction that gave about 10 nm fetch, resulting in 20 - 30 cm (8 - 12") waves. I reefed again. The water stay was a little loose, an...
- Sun Jul 23, 2023 9:32 pm
- Forum: Hydrofoils
- Topic: Hinged Bruce foiler
- Replies: 9
- Views: 102522
Re: Hinged Bruce foiler
I can see from your last photograph that the foil is pitched up (positive angle of attack even when no leeway) with the boat floating level. That picture is a little misleading because the boat is on the dock, which is not quite level. And this is pretty much the pitch angle the foil was supposed t...
- Mon Jul 17, 2023 7:47 pm
- Forum: Hydrofoils
- Topic: Hinged Bruce foiler
- Replies: 9
- Views: 102522
Re: Hinged Bruce foiler
Exams are done, and I could sail a bit more. The mast is not yet reinforced. Epoxy resin with both a good mix ratio and a slow hardener turns out to be rather more difficult to get hold of than I expected. I had a Norwegian supplier for Aeropoxy, but they stopped stocking the slow hardener, and the ...
- Wed May 31, 2023 7:09 pm
- Forum: Hydrofoils
- Topic: Hinged Bruce foiler
- Replies: 9
- Views: 102522
Re: Hinged Bruce foiler
The boat has been on the water in winds around 4 knots, gusting to 10, suitable for a gentle first test. https://www.boatdesign.net/gallery/hinged-bruce-foiler-assembled.29528/full The foil stabilises the boat nicely when to lee, in so far as I could test in the gentle wind I had. When to weather, t...
- Sat Dec 10, 2022 7:37 am
- Forum: Hydrofoils
- Topic: Hinged Bruce foiler
- Replies: 9
- Views: 102522
Re: Hinged Bruce foiler
my interpretation of your diagrams is that on the 'Lee tack' the arm supporting the hinge for the 'foil arm' is locked, so the system operates much like Gerald Holtom's foiling boats. Then you unlock the hinge as your tack? Yes. The figure in the first post is inconsistent. On the left, I drew, in ...
- Wed Dec 07, 2022 9:58 pm
- Forum: Hydrofoils
- Topic: Hinged Bruce foiler
- Replies: 9
- Views: 102522
Re: Hinged Bruce foiler
The boat is finished. All that remains to be done is set up the running rigging, and wait for the beginning of the sailing season, in about half a year Here you can see the boat with the frame tied to the hull, and the foil and beam upside down besides it. I can probably cut off the last two rungs o...
- Mon Jun 20, 2022 6:50 pm
- Forum: Craft
- Topic: Pedal boat
- Replies: 0
- Views: 19012
Pedal boat
This is genius:
https://www.youtube.com/watch?v=HFS1ZJ2x41s&t
How come I never heard of this? The patent is from 1985, which should have been enough time for it to succeed.
https://www.youtube.com/watch?v=HFS1ZJ2x41s&t
How come I never heard of this? The patent is from 1985, which should have been enough time for it to succeed.
- Sat Nov 20, 2021 6:12 pm
- Forum: Hydrofoils
- Topic: Hinged Bruce foiler
- Replies: 9
- Views: 102522
Hinged Bruce foiler
Following a query during November's meeting, I will report here on my (very slow) progress on my main project, "Insert Hull Here", a frame with hinged Bruce foil. It is intended to contain all the forces generated by the rig and the underwater appendages within the frame, so that the hull only has t...
- Tue Aug 31, 2021 12:31 am
- Forum: Sails & Aerodynamics
- Topic: Sail polar diagram
- Replies: 4
- Views: 55474
Re: Sail polar diagram
A few more papers
- Sat Aug 14, 2021 12:56 pm
- Forum: Sails & Aerodynamics
- Topic: Sail polar diagram
- Replies: 4
- Views: 55474
Re: Sail polar diagram
Those who are interested in a sail would want to separate the properties of the sail from those of the hull, so you get tests of a sail alone. That said, data including a hull are what you need for a Velocity Prediction Program, so the relevant data, or models, must exist. I don't know whether they ...
- Sat Aug 07, 2021 4:32 pm
- Forum: Sails & Aerodynamics
- Topic: Sail polar diagram
- Replies: 4
- Views: 55474
Re: Sail polar diagram
I expect you know Marchaj, and I attach another source, for oceanic sails. This paper is for the Tornado, but has references that look useful: https://link.springer.com/article/10.1007%2Fs00773-008-0007-4#Bib1 Then there is Fujiwara et al. (2003) On aerodynamic characteristics of a hybrid-sail with ...
- Sun Jun 13, 2021 4:33 pm
- Forum: Hydrofoils
- Topic: V-Rex, a large, Moth-style foiler
- Replies: 1
- Views: 19019
V-Rex, a large, Moth-style foiler
There is a Kickstarter project for a large foiler, intended to break offshore speed record, which can supposedly be scaled up for cargo transport: https://www.kickstarter.com/projects/v-rex/emission-free-speed-record-and-offshore-transportation https://ksr-ugc.imgix.net/assets/033/540/629/f8acba01ea...
- Sun Mar 14, 2021 1:23 pm
- Forum: Hulls & Keels
- Topic: Historical examples of one-way outrigger boats
- Replies: 1
- Views: 62463
Historical examples of one-way outrigger boats
At http://www.tackingoutrigger.com/kilakarai.html , Peter Evans cites a description of the Kilakarai outrigger boat. The description is an excerpt from "The Origins and Ethnological Significance Of Indian Boat Designs" (1920) by James Hornell, the Director of Fisheries for the Madras government. Eva...
- Sat Feb 13, 2021 1:05 pm
- Forum: Wind- & Water-turbines, Propellors, Human power
- Topic: Alan Craig's oscillating fin & Ken Kingsbury's Foil Rower
- Replies: 0
- Views: 26374
Alan Craig's oscillating fin & Ken Kingsbury's Foil Rower
I have been thinking about Alan Craig's oscillating fin drive, and what I can infer from Ken Kingsbury's Foil Rower: https://www.youtube.com/watch?v=tcNaV3_3n3U As far as I can tell from 0:55 - 0:58, those foils are rigid. There seems to be no attempt to make them twist, like the fins of the Hobie M...
- Wed Jan 20, 2021 2:29 pm
- Forum: Welcome to the AYRS Forums
- Topic: Hello from SF Bay - Tilt wing
- Replies: 4
- Views: 26447
Re: Hello from SF Bay - Tilt wing
The closest I know to what you seem to have in mind is Dingbat. There is a web site, but it hasn't been updated since 2008: https://www.dingbat.com.au/Latest.html I have been idly thinking about doing something similar with a KiteWing ( https://kitewing.com/ ), which is a hand held 4sqm wing that re...
- Tue Dec 15, 2020 10:24 pm
- Forum: Technical Papers for review and comment
- Topic: Howard Fund
- Replies: 38
- Views: 16777215
Re: Howard Fund
I forgot that the masts are a bit ahead of the rotation axis.
Even so, can the rig be rotated so far that the forward and aft sails are along a line parallel to the centreline? Could the forward sail be sheeted in far enough for upwind work? That should still be the closest comparison to a sloop.
Even so, can the rig be rotated so far that the forward and aft sails are along a line parallel to the centreline? Could the forward sail be sheeted in far enough for upwind work? That should still be the closest comparison to a sloop.
- Tue Dec 08, 2020 12:14 am
- Forum: Technical Papers for review and comment
- Topic: Howard Fund
- Replies: 38
- Views: 16777215
Re: Howard Fund
Nice data, but how did you derive the polar for the hypothetical sloop? I have a suggestion for getting real data: in the next season, generate another set of polars with the two masts of your Duplex rig always on the centreline. I expect the sheeting won't let you simulate sailing wing and wing the...
- Sat Oct 24, 2020 2:28 pm
- Forum: Craft
- Topic: Syroco proposal for Sailing Speed Record Challenger
- Replies: 3
- Views: 17554
Re: Syroco proposal for Sailing Speed Record Challenger
Did you find a video on the Syroco web site? The link that I originally followed was to this video: https://www.youtube.com/watch?v=Blb2S6Ytngg It is clear from these videos that the hull does not revolve arround its longitudinal axis when the craft tacks. There appears to be a cylinder within the ...
- Thu Oct 22, 2020 7:39 pm
- Forum: Craft
- Topic: Syroco proposal for Sailing Speed Record Challenger
- Replies: 3
- Views: 17554
Re: Syroco proposal for Sailing Speed Record Challenger
Syroco looks to me like Jon Howes’ Monofoil with a kite instead of a wing. The most significant difference seems to be that Syroco is supposed to tack, though I don't understand how that is supposed to work. Maybe the apparent tack is only an illustration that Syroco can sail on both tacks. With the...
- Sat Sep 05, 2020 11:11 am
- Forum: Craft
- Topic: Asymmetric outrigger hulls or amas
- Replies: 2
- Views: 17576
Re: Asymmetric outrigger hulls or amas
I'm planning to build a drop in outrigger assembly to convert a canoe or similar small boat to a trimaran for sailing. I have tried drop in assemblies, though not yet a trimaran. My additional constraints are that I have previously used an Ally 17 folding canoe, with a skin over and aluminium frame...
- Mon Jun 15, 2020 2:30 pm
- Forum: Craft
- Topic: Antifouling
- Replies: 1
- Views: 13185
Antifouling
Here is a news item on an antifouling, superhydrophobic diamond film, which is supposed to be robust, too: https://phys.org/news/2020-06-antibiofouling-biomimetic-diamond.html This is still basic research, so it will be a while until it becomes clear whether it will ever come to market. I have been ...
- Thu May 02, 2019 8:47 pm
- Forum: Craft
- Topic: Boat with suspension
- Replies: 0
- Views: 31549
Boat with suspension
Nauti craft (http://www.nauti-craft.com/) makes boats with suspension: https://www.youtube.com/watch?v=kCgVumRpLro. I suppose a small waterplane area does much the same thing, but perhaps the advantage of the suspension is shallower draft and the option of active control.
- Fri Mar 08, 2019 1:13 am
- Forum: Sails & Aerodynamics
- Topic: Request for collaboration
- Replies: 18
- Views: 64747
Re: Request for collaboration
On the other hand, if you want an autonomous sailing vessel with good performance perhaps you should be talking to the Artemis Technologies people: http://www.artemisracing.com/en/technologies/home.html The use case I was thinking of would include this: https://www.nationalgeographic.com/animals/20...
- Mon Mar 04, 2019 2:28 am
- Forum: Sails & Aerodynamics
- Topic: Request for collaboration
- Replies: 18
- Views: 64747
Re: Request for collaboration
The picture below is an interpretation of the aerostat with (approximately) vertical wing. That was pretty much my starting point. I can see that you could use a bridle attached at wing tip and wing root but I think the attachments would need to be on the leading edge of the wing That is the intent...
- Wed Feb 13, 2019 10:45 pm
- Forum: Sails & Aerodynamics
- Topic: Request for collaboration
- Replies: 18
- Views: 64747
Re: Request for collaboration
Could you thing at a blimp/kite that could be shaped like an thick hollow square box inflated with hydrogen or helium. Horizontal surfaces could be your wings and the vertical surfaces could serve to maintain the direction. I must be misinterp0reting something, because my mental image now is of a c...
- Sat Feb 09, 2019 11:33 pm
- Forum: Sails & Aerodynamics
- Topic: Request for collaboration
- Replies: 18
- Views: 64747
Re: Request for collaboration
I had to look up the definition of 'aerostat' - apparently it means any aircraft using lighter than air gas foy bouyancy, e.g. powered airship, balloon, hot air or gas. I came across the term when I looked up what to call something held aloft by gas, streamlined, and tethered. It was the tether tha...
- Sun Dec 23, 2018 10:21 pm
- Forum: Sails & Aerodynamics
- Topic: Request for collaboration
- Replies: 18
- Views: 64747
Re: Request for collaboration
I just lost two hopurs of typing a reply, because the system logged me out before I clicked on "Preview", then didn't take me backl to what I had written after I logged in again. I have to see when I have time to write this again. Probably a week or so.
- Sun Dec 23, 2018 7:41 pm
- Forum: Sails & Aerodynamics
- Topic: Request for collaboration
- Replies: 18
- Views: 64747
Re: Request for collaboration
Robert, I guess that what you meant to say is the the torsional strength of individual beams makes a negligible contribution to the torsional STRENGTH of the whole structure. Strength and stiffness are different properties! (and both are important in boat designing) Probably. I had assumed that if ...
- Sun Dec 16, 2018 2:03 am
- Forum: Sails & Aerodynamics
- Topic: Request for collaboration
- Replies: 18
- Views: 64747
Re: Request for collaboration
and partly from the moment of inertia that comes from the distance between beams. Robert: Quoting part of a sentence from you message, I think the above is a misconception. Considering two hulls joined by two cross beams, it is true that as the craft as a whole is twisted (i.e. one bow and an oppos...
- Sun Dec 16, 2018 1:41 am
- Forum: Sails & Aerodynamics
- Topic: Request for collaboration
- Replies: 18
- Views: 64747
Re: Request for collaboration
Presumably you are aware of the work done by Didier Costes and the airships Zeppy 1 (1985) and Zeppy 2 (1992) and Zeppy 3 (2008). I have read what was Costes published in Ultimate Sailing IV (I think), and whatever I could find on the net. I got the impression that Costes now is an advisor, and tha...
- Mon Dec 10, 2018 1:00 am
- Forum: Sails & Aerodynamics
- Topic: Request for collaboration
- Replies: 18
- Views: 64747
Request for collaboration
I think I know how to work out the passive stability of the elevation angle of an airship used as a sail. I had the idea oever a year ago, but I have other projects, both professional and boat related, with higher priority, so nothing has happened. Is anyone interested in a collaboration? The projec...
- Tue Dec 04, 2018 6:56 pm
- Forum: Hulls & Keels
- Topic: Constant Camber (tm)
- Replies: 4
- Views: 21497
Re: Constant Camber (tm)
The thing I really want is how to design to the technique. More "recipe" and less "high concept"! As I understand it, the panels you can make are cuts through the torus. That sounds like a job for a 3D rendering programme. That wouldn't tell you how to combine panels if you want more than one panel...
- Tue Dec 04, 2018 6:39 pm
- Forum: Hydrofoils
- Topic: Trifoiler-style foils on IMOCAs?
- Replies: 6
- Views: 27722
Re: Trifoiler-style foils on IMOCAs?
Thinking about this again, I think there is a basic problem in applying Trifoiler type foils, or wand controlled foils, or indeed any surface tracking foils to IMOCA 60s. The problem is that the IMOCA boats are currently sailed at large heel angles, so a Trifoiler type foil mounted from the side of...
- Sat Nov 10, 2018 8:32 pm
- Forum: Hulls & Keels
- Topic: Constant Camber (tm)
- Replies: 4
- Views: 21497
Re: Constant Camber (tm)
There is some information in this book: http://outrigmedia.com/outrig/wp-content/uploads/support/among-the-multihulls-volume-two.pdf It's not a manual, though. The patent is here: https://patents.google.com/patent/US4471710 I found what looks like the exact same idea, only using a female mold, paten...
- Thu Nov 08, 2018 9:26 pm
- Forum: Hydrofoils
- Topic: Trifoiler-style foils on IMOCAs?
- Replies: 6
- Views: 27722
Re: Trifoiler-style foils on IMOCAs?
By Trifoiler style foils do you mean fully immersed inverted Tee foils that have flaps linked (as with the Moth main foil) No. The Trifoiler uses L-foils linked to sensor surfaces well ahead of the foil. See https://www.youtube.com/watch?v=zXSgZCDVWOM The rules require foils to be retractable, an e...
- Mon Oct 22, 2018 5:56 pm
- Forum: Hulls & Keels
- Topic: Hull impact resistance
- Replies: 4
- Views: 56137
Re: Hull impact resistance
you can usually prove what you want to prove by choosing suitable test specimens and test procedure. Yes, that was downright cheeky. That wood seemed to be not plywood, but a plank with the grain parallel to the supports, not going across from one side to the other. Of course it bloody broke. Unidi...
- Thu Oct 11, 2018 8:43 pm
- Forum: Hulls & Keels
- Topic: Hull impact resistance
- Replies: 4
- Views: 56137
Re: Hull impact resistance
The common test seems to be to take a standardised shape, with standardised weight, and drop it from a variable height. How pointy the shape is matters. I think it was Gerr who told the story of a boat builder who handed around a lightweight kevlar panel and a claw hammer, inviting people to hit the...
- Thu Oct 11, 2018 3:53 pm
- Forum: Sails & Aerodynamics
- Topic: Morley tethered kite sail
- Replies: 1
- Views: 18481
Morley tethered kite sail
I think I can rephrase Morley's interpretation of the results of the Morley tethered kite sail test reported in Catalyst 50 so that they are a bit more intuitive. One part of the argument is in this pair of diagrams: https://i.stack.imgur.com/00DJ7.jpg The point of the steepest slope on the left, fo...
- Thu Oct 11, 2018 3:03 pm
- Forum: Sails & Aerodynamics
- Topic: Parasol rig: Pilcher of London and Wilson of Dublin demonstrate their 'Cyclone' yacht
- Replies: 3
- Views: 17863
Re: Parasol rig: Pilcher of London and Wilson of Dublin demonstrate their 'Cyclone' yacht
I found the entry in Marchaj. The photo has a better resolution than what I found online, but still not quite enough. I also found a letter that Pilcher sent to the journal Nature in 1897 ( https://www.nature.com/articles/056342a0 ). That is a bit more informative. Pilcher first descrobes the idea o...
- Sat Sep 29, 2018 6:30 pm
- Forum: Sails & Aerodynamics
- Topic: Parasol rig: Pilcher of London and Wilson of Dublin demonstrate their 'Cyclone' yacht
- Replies: 3
- Views: 17863
Re: Parasol rig: Pilcher of London and Wilson of Dublin demonstrate their 'Cyclone' yacht
My university library has it. I ordered the 1979 edition, because the 2000 edition is already out on loan. I'll see what I can find. What I specifically want to know is whether the sail was at a fixed angle relative to the mast. The photographs don't have high enough resolution to tell me. The drawi...
- Sat Sep 29, 2018 1:07 am
- Forum: Sails & Aerodynamics
- Topic: Parasol rig: Pilcher of London and Wilson of Dublin demonstrate their 'Cyclone' yacht
- Replies: 3
- Views: 17863
Parasol rig: Pilcher of London and Wilson of Dublin demonstrate their 'Cyclone' yacht
Does anyone know anything about the boat in these pictures? https://www.prints-online.com/parasol-yacht-602267.html https://www.scienceandsociety.co.uk/results.asp?image=10311101 https://www.prints-online.com/royal-aeronautical-society/photographic/pilcher-boat-umbrella-sail-9905275.html Google tran...
- Mon Sep 10, 2018 7:44 pm
- Forum: Hydrofoils
- Topic: Trifoiler-style foils on IMOCAs?
- Replies: 6
- Views: 27722
Trifoiler-style foils on IMOCAs?
Is there anything to prevent IMOCAs from using Trifoiler-style foils on either side of the hull, perhaps attached to the outriggers that provide a broad base for the standing rigging? One constraint is that there should be only one degree of freedom to how the foils move, but that condition would be...
- Sun Jun 04, 2017 9:42 am
- Forum: Hydrofoils
- Topic: Sonic tubes
- Replies: 1
- Views: 16321
Sonic tubes
The designer of the Rave V foiling trimaran says that sonic tubes at the junction of V-foils reduce cavitation. See https://www.youtube.com/watch?t=228&v=JD5-shtZalY from 12:30. Does anyone know how these work? When I search for "sonic lifting tube," I only get sites associated with the Rave V, asse...
- Fri May 12, 2017 11:54 pm
- Forum: Craft
- Topic: The WindFly Rig - Fast and stable kite boats - no heel, no leeway
- Replies: 5
- Views: 24077
Re: The WindFly Rig - Fast and stable kite boats - no heel, no leeway
I have a read a bit more. Your WindFly rig is the most interesting boat-related idea I have seen in a long time. It is original, innovative, small and simple enough that it shouldn't be horrendously expensive, and could be applied to an enormous number of boats: everything that is driven by an outbo...
- Sat May 06, 2017 10:29 pm
- Forum: Craft
- Topic: The WindFly Rig - Fast and stable kite boats - no heel, no leeway
- Replies: 5
- Views: 24077
Re: The WindFly Rig - Fast and stable kite boats - no heel, no leeway
For a few seconds, I thought this was like Ingo Voegler's setup (https://www.youtube.com/watch?v=ruBQ1CM_VUA), but once I read a bit more, I found that you are trying to achieve a whole lot more. I really want to know how it works out, so please do write that article, and make a few videos. I'd offe...
- Wed Apr 12, 2017 6:04 pm
- Forum: Craft
- Topic: MicroTransat
- Replies: 21
- Views: 78745
Re: MicroTransat
If the sailing airship is one of the options you will consider, email me.
- Sun Mar 26, 2017 9:31 pm
- Forum: Technical Papers for review and comment
- Topic: Howard Fund
- Replies: 38
- Views: 16777215
Re: Howard Fund
For sure a wishbone could surely do the work too! But... - Some are not so effective for fine tuning the sails. Because you can't separate outhaul from leach tension? I think that could be done if you have a vang to regulate the vertical position of the end of the boom, and you attach the clew to a...
- Wed Mar 22, 2017 9:01 pm
- Forum: Members Sales and Wants
- Topic: C-class Emma Hamilton for sale on EBay
- Replies: 1
- Views: 15250
C-class Emma Hamilton for sale on EBay
It's not me who is selling, but it seems AYRS members in the UK might be interested in buying a C-class cat: http://www.ebay.co.uk/itm/C-CLASS-CATAM ... Sw32lYwmv6
- Wed Mar 22, 2017 8:57 pm
- Forum: Technical Papers for review and comment
- Topic: Howard Fund
- Replies: 38
- Views: 16777215
Re: Howard Fund
Actually, the rig is completed too; I'm now working on booms that are also quiet unusual. That was going to be my next question. I noticed the model has conventional booms and no apparent control over twist. There doesn't seem enough leverage for a vang, and a traveller might have problems with mas...
- Tue Mar 14, 2017 7:48 pm
- Forum: Technical Papers for review and comment
- Topic: Howard Fund
- Replies: 38
- Views: 16777215
Re: Howard Fund
I'm the kind of helsman who like to sail with a long stick up to my shoulder and between two fingers! You can not do that with twin rudders. Me, too, but back when I sailed a Hobie 14, that's how I had it set up, and with much of the lateral resistance being provided by the rudders, they saw some l...
- Sun Mar 12, 2017 7:23 pm
- Forum: Technical Papers for review and comment
- Topic: Howard Fund
- Replies: 38
- Views: 16777215
Re: Howard Fund
Have you decided how to attach the masts to the circular track? I suppose that connection must cope with compression as well as upwards pull. And I think sail forces will always push the whole kaboodle to lee, so you must actively control the angle of the mast assembly to the wind? Rotation of the m...
- Thu Mar 09, 2017 7:42 pm
- Forum: Hulls & Keels
- Topic: Transonic hull
- Replies: 7
- Views: 28218
Re: Transonic hull
I first came across the transonic hull on the proa forum, where someone suggested that two of them joined end-to-end might make a good proa hull. I found that so counterintuitive that I looked it up, and a few days later found your report in the latest Catalyst. And today, I came across a crowdfundi...
- Thu Mar 09, 2017 7:38 pm
- Forum: Technical Papers for review and comment
- Topic: Howard Fund
- Replies: 38
- Views: 16777215
Re: Howard Fund
One of Dashew's books has a picture of an Open 60 (or possibly a predecessor to that design rule) with such a rudder. I think it was called a tilting rudder there. I also saw it on Mudskipper, a steel cruising boat from Australia that came to Trondheim. There are pictures in one of the Junk rig Asso...
- Thu Feb 23, 2017 9:22 pm
- Forum: Technical Papers for review and comment
- Topic: Proposal: Sail Performance Analysis Rig (SPAR)
- Replies: 7
- Views: 27444
Re: Proposal: Sail Performance Analysis Rig (SPAR)
Your diagram describes something not physically possible. You have negative drag. If that existed, we could build a perpetuum mobile. Imagine your sail were mounted on a wind turbine hub, in a dead calm. Assume that the vertical line that shows wind direction is the plane of rotation. Push the rig w...
- Mon Feb 20, 2017 5:46 pm
- Forum: Technical Papers for review and comment
- Topic: Proposal: Sail Performance Analysis Rig (SPAR)
- Replies: 7
- Views: 27444
Re: Proposal: Sail Performance Analysis Rig (SPAR)
As an amateur, I'm pretty much solely interested in comparing competing equivalent sail forms in terms of forward thrust generated by the sail, relative to the wind across a range of sheeting angles, and the cost in heeling force. Both of these seem to be indicated by mast heel deflection in the SP...
- Sat Feb 18, 2017 4:26 pm
- Forum: Craft
- Topic: MicroTransat
- Replies: 21
- Views: 78745
Re: MicroTransat
It would increase displacement, though. It doesn't matter to displacement whether you carry the weight in the form of water or something else. If you start thinking of a hull, then mentally add a water-filled keel, you don't need to make other alterations to the hull, and that can give the impressio...
- Thu Feb 16, 2017 7:47 pm
- Forum: Craft
- Topic: MicroTransat
- Replies: 21
- Views: 78745
Re: MicroTransat
I wondered if a trimaran with a water filled ballast keel to allow recovery from knockdown Why water ballast? For a given weight, lead would give you a lower centre of gravity. The advantage of water ballast is the ability to dump it or take in more. That seems an unnecessary complication while und...
- Thu Feb 16, 2017 7:40 pm
- Forum: Technical Papers for review and comment
- Topic: Proposal: Sail Performance Analysis Rig (SPAR)
- Replies: 7
- Views: 27444
Re: Proposal: Sail Performance Analysis Rig (SPAR)
I can see how knowing the direction of the wind and of the deflection at the base gives you the lift to drag ratio, but only if any vertical sheeting forces are contained within the rig, through a really strong vang, or a wishbone boom. Sheeting as shown in the picture would pull the rig back and mi...
- Sat Feb 04, 2017 5:34 pm
- Forum: Craft
- Topic: Mark Hillman's proa
- Replies: 0
- Views: 32286
Mark Hillman's proa
If the top bends, it eases gust loads The sheeting is not specified in the Catalyst article. If it is as with a lug sail, single sheet and control twist partly by tension on the tack line and partly by how much sail is before the mast, then I can see that happening. If the plan is to use junk.rig-s...
- Sun Jan 29, 2017 6:20 pm
- Forum: Craft
- Topic: Autonomous ships
- Replies: 2
- Views: 19650
Re: Autonomous ships
It won't be long before we all need to have AIS receivers I have read reports of Large cargo ships being built with a view to no crew, trials initially with monitoring by a crew on board and later with just computer observation from shorebased offices; presumably after that, let loose on their own ...
- Sat Jan 28, 2017 6:05 pm
- Forum: Hulls & Keels
- Topic: Transonic hull
- Replies: 7
- Views: 28218
Re: Transonic hull
Caveat - I've never seen one of these hulls in action ... The pictures in the paper are reasonably consistent with the claim, but video would be nice. I suspect that if you work out the curve of cross-sectional areas, and built another hull with the same curve it would have the same wave making cha...
- Wed Jan 25, 2017 8:54 pm
- Forum: Hulls & Keels
- Topic: Transonic hull
- Replies: 7
- Views: 28218
Transonic hull
At http://www.din.unina.it/HSMV%202011%20Proceedings/html/Papers/28.pdf there is a description of a hull shape intended not to make waves. One of the postulates which led to the development of the described hull shape, a tetrahedron with rounded edges is: If such new shape avoids curvature in its wa...
- Wed Jan 25, 2017 8:26 pm
- Forum: Craft
- Topic: MicroTransat
- Replies: 21
- Views: 78745
Re: MicroTransat
My purpose in approaching your society is to seek your opinion as to whether you consider the idea of building a vessel (max length 4m) propelled by wind power only and to send it on a mission to traverse the Atlantic completely autonomously is feasible. I know it’s feasible for a moderately-sized ...