Search found 10 matches

by Robert Biegler
Thu Feb 23, 2017 9:22 pm
Forum: Technical Papers for review and comment
Topic: Proposal: Sail Performance Analysis Rig (SPAR)
Replies: 7
Views: 88

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...
by Robert Biegler
Mon Feb 20, 2017 5:46 pm
Forum: Technical Papers for review and comment
Topic: Proposal: Sail Performance Analysis Rig (SPAR)
Replies: 7
Views: 88

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...
by Robert Biegler
Sat Feb 18, 2017 4:26 pm
Forum: Boats
Topic: MicroTransat
Replies: 6
Views: 248

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...
by Robert Biegler
Thu Feb 16, 2017 7:47 pm
Forum: Boats
Topic: MicroTransat
Replies: 6
Views: 248

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...
by Robert Biegler
Thu Feb 16, 2017 7:40 pm
Forum: Technical Papers for review and comment
Topic: Proposal: Sail Performance Analysis Rig (SPAR)
Replies: 7
Views: 88

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...
by Robert Biegler
Sat Feb 04, 2017 5:34 pm
Forum: Technical Papers for review and comment
Topic: Mark Hillman's proa
Replies: 0
Views: 64

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...
by Robert Biegler
Sun Jan 29, 2017 6:20 pm
Forum: Gossip & other snippets
Topic: Autonomous ships
Replies: 2
Views: 340

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 ...
by Robert Biegler
Sat Jan 28, 2017 6:05 pm
Forum: Hulls & Keels
Topic: Transonic hull
Replies: 3
Views: 214

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...
by Robert Biegler
Wed Jan 25, 2017 8:54 pm
Forum: Hulls & Keels
Topic: Transonic hull
Replies: 3
Views: 214

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...
by Robert Biegler
Wed Jan 25, 2017 8:26 pm
Forum: Boats
Topic: MicroTransat
Replies: 6
Views: 248

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 ...

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