magnetman Posted April 15 Report Share Posted April 15 I meant anti ventilation plates. Link to comment Share on other sites More sharing options...
Tony Brooks Posted April 15 Report Share Posted April 15 10 minutes ago, magnetman said: I meant anti ventilation plates. Of course you did. The trouble is that those who know the difference between cavitation and ventilation on props are not as numerous who think both are the same thing. 1 Link to comment Share on other sites More sharing options...
MtB Posted April 15 Report Share Posted April 15 24 minutes ago, Tony Brooks said: Of course you did. The trouble is that those who know the difference between cavitation and ventilation on props are not as numerous who think both are the same thing. I'd imagine with a cavitation problem, welding on anti-ventilation plates would make no difference or could make it worse, if anything. Link to comment Share on other sites More sharing options...
Tony Brooks Posted April 15 Report Share Posted April 15 18 minutes ago, MtB said: I'd imagine with a cavitation problem, welding on anti-ventilation plates would make no difference or could make it worse, if anything. I agree, but not sure how it could make things worse because cavitation air/gas bubbles are caused by the prop itself making low pressure areas, not drawing air down from the surface. Link to comment Share on other sites More sharing options...
MtB Posted April 15 Report Share Posted April 15 47 minutes ago, Tony Brooks said: I agree, but not sure how it could make things worse because cavitation air/gas bubbles are caused by the prop itself making low pressure areas, not drawing air down from the surface. I was thinking they might marginally further restrict the flow of water into the prop, making cavitation slightly worse. Link to comment Share on other sites More sharing options...
Tony Brooks Posted April 15 Report Share Posted April 15 4 minutes ago, MtB said: I was thinking they might marginally further restrict the flow of water into the prop, making cavitation slightly worse. That is certainly a possibility, but if it restricted much I think it would ventilate because that means water would have been drawing down from the surface. Link to comment Share on other sites More sharing options...
Derek R. Posted April 16 Report Share Posted April 16 Well I'll show my further ignorance by asking; What is an anti-ventilation plate, and how does it differ from an anti-cavitation plate? Where is it fitted, what does it do? The correction needs an explanation. (At least for me it would appear). Link to comment Share on other sites More sharing options...
BEngo Posted April 16 Report Share Posted April 16 (edited) Ventilation is when air is drawn down from the surface into the propellor, spoiling its thrust. Cavitation is when the pressure at the front face of the propellor blades is low enough for tiny steam bubbles to form ( boiling ) in spots. When the bubbles collapse there is often damage to the propellor, and a lot of underwater noise. Anti ventilation plates as seen on many converted butties e.g. Renown, stop air drawing down and are a substitute for the motors counter plate. Anti cavitation plates do not exist. Cavitation is dealt with by extra immersion and careful propulsion system design N Edited April 16 by BEngo 1 Link to comment Share on other sites More sharing options...
Derek R. Posted April 16 Report Share Posted April 16 https://www.boatingbasicsonline.com/boat-propeller-cavitation-vs-ventilation/ Link to comment Share on other sites More sharing options...
magnetman Posted April 16 Report Share Posted April 16 (edited) The motorised former horse Boat I owned briefly had anti ventilation plates. The Raven butty had a very similar arrangement but I don't think it had the flanged edges so if you fell in at the wrong time it would cut you in half. This was the Boat I had: https://www.nationalhistoricships.org.uk/sites/default/files/data/nrhv/vessels/2087_ORIANNE_5.jpg Edited April 16 by magnetman Link to comment Share on other sites More sharing options...
IanM Posted April 16 Report Share Posted April 16 41 minutes ago, magnetman said: The motorised former horse Boat I owned briefly had anti ventilation plates. The Raven butty had a very similar arrangement but I don't think it had the flanged edges so if you fell in at the wrong time it would cut you in half. This was the Boat I had: https://www.nationalhistoricships.org.uk/sites/default/files/data/nrhv/vessels/2087_ORIANNE_5.jpg Enlarged picture of Raven from the other end to my previous picture showing the plates being discussed. Actually it looks to be more of a single plate as it wraps around the stern but whatever 1 Link to comment Share on other sites More sharing options...
Ray T Posted April 16 Report Share Posted April 16 (edited) On 16/04/2024 at 08:18, BEngo said: Ventilation is when air is drawn down from the surface into the propellor, spoiling its thrust. Cavitation is when the pressure at the front face of the propellor blades is low enough for tiny steam bubbles to form ( boiling ) in spots. When the bubbles collapse there is often damage to the propellor, and a lot of underwater noise. Anti ventilation plates as seen on many converted butties e.g. Renown, stop air drawing down and are a substitute for the motors counter plate. Anti cavitation plates do not exist. Cavitation is dealt with by extra immersion and careful propulsion system design N Photo from here: http://nurser.co.uk/index.html Edited April 17 by Ray T 1 Link to comment Share on other sites More sharing options...
max's son Posted April 19 Report Share Posted April 19 On 07/04/2024 at 17:29, Paul H said: And Vesta has been (finally) sold… Paul See that Ballinger has also sold Link to comment Share on other sites More sharing options...
ditchcrawler Posted April 26 Report Share Posted April 26 Up on Facebook Link to comment Share on other sites More sharing options...
Admiral Posted May 13 Report Share Posted May 13 Gort for sale Gort Link to comment Share on other sites More sharing options...
David Mack Posted May 13 Report Share Posted May 13 21 minutes ago, Admiral said: Gort for sale Gort We accompanied Gort up the Grand Union after the Diamond Jubilee Parade on the Thames in 2012. The owner is a lovely chap, and from spending a few days boating, and a couple of evenings in the pub with him, I would never have guessed he was a Peer of the Realm! Link to comment Share on other sites More sharing options...
Ray T Posted May 14 Report Share Posted May 14 Gort was Mike H's first boat as captain. I met the owner and boat a few years ago now at Sutton Stop. I was privileged to be allowed in the cabin. A beautifully maintained boat. Link to comment Share on other sites More sharing options...
Stroudwater1 Posted May 14 Report Share Posted May 14 6 hours ago, Ray T said: Gort was Mike H's first boat as captain. I met the owner and boat a few years ago now at Sutton Stop. I was privileged to be allowed in the cabin. A beautifully maintained boat. We let Gort past us last year round Wolfhampcote, lovely engine noise and a beautiful boat. I hope someone who appreciates and can look after her is tempted. Re an anti ventilation plate - does this one count? Link to comment Share on other sites More sharing options...
mrsmelly Posted May 15 Report Share Posted May 15 13 hours ago, Stroudwater1 said: We let Gort past us last year round Wolfhampcote, lovely engine noise and a beautiful boat. I hope someone who appreciates and can look after her is tempted. Re an anti ventilation plate - does this one count? I used to moor next to that boat lol. 1 Link to comment Share on other sites More sharing options...
Admiral Posted May 16 Report Share Posted May 16 James Henry bantock for sale on the duck James Henry Link to comment Share on other sites More sharing options...
cuthound Posted May 17 Report Share Posted May 17 12 hours ago, Admiral said: James Henry bantock for sale on the duck James Henry Phil and Margaret Dowling's old boat, so would have been well looked after at least until he died a few years ago. They were a lovely couple who used to manage the Black Prince hire base at Northwich. It was one of the better moorings for our shareboat. Link to comment Share on other sites More sharing options...
ditchcrawler Posted May 17 Report Share Posted May 17 17 hours ago, Admiral said: James Henry bantock for sale on the duck James Henry @haggis have you seen this? Link to comment Share on other sites More sharing options...
haggis Posted May 17 Report Share Posted May 17 1 hour ago, ditchcrawler said: @haggis have you seen this? I knew it was going to be sold as Margaret no longer lives on board. I will miss seeing her when we pass Link to comment Share on other sites More sharing options...
Foggy66 Posted May 21 Report Share Posted May 21 Wooden motor https://www.facebook.com/groups/canalsandrivers/permalink/7681189938631868/for Link to comment Share on other sites More sharing options...
David Mack Posted May 21 Report Share Posted May 21 4 hours ago, Foggy66 said: Wooden motor https://www.facebook.com/groups/canalsandrivers/permalink/7681189938631868/for And for those of us that aren't members of the private Facebook group? Link to comment Share on other sites More sharing options...
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