Search found 44 matches

by John Perry
Wed Sep 11, 2019 10:56 am
Forum: Events & other announcements
Topic: AYRS meeting at the Basingstoke Canal Centre - 21 & 22 September 2019
Replies: 2
Views: 1072

Re: AYRS meeting at the Basingstoke Canal Centre - 21 & 22 September 2019

With the proposed towing tests now less than 2 weeks away I spent yesterday rigging up a load cell with an arduino microcontroller. It will need to be connected to a laptop to use it, I don't think I have time to include data display and storage at this stage. The need to take a laptop afloat could ...
by John Perry
Sun Sep 08, 2019 12:02 pm
Forum: Monohulls
Topic: AC 75 Now Afloat
Replies: 0
Views: 62

AC 75 Now Afloat

Well, the first AC 75 is now afloat, there are a few videos on the internet, e.g. https://www.youtube.com/watch?v=VuI1ILwo7tI When we first saw the concept I expect that some of us wondered if it would even stay upright in a flat calm. Well I expect it will but we still dont have confirmation of tha...
by John Perry
Sun Sep 08, 2019 9:52 am
Forum: Events & other announcements
Topic: AYRS meeting at the Basingstoke Canal Centre - 21 & 22 September 2019
Replies: 2
Views: 1072

Re: AYRS meeting at the Basingstoke Canal Centre - 21 & 22 September 2019

This event is now two weeks away. Not all our members read the posts on this forum so I have sent an announcement to all members within approximately 80 miles of the venue in Surrey UK, using email for those members who have provided the AYRS with an email address and post for those who have not. Th...
by John Perry
Wed Feb 20, 2019 4:37 pm
Forum: Sails & Aerodynamics
Topic: Request for collaboration
Replies: 18
Views: 5964

Re: Request for collaboration

The picture below is an interpretation of the aerostat with (approximately) vertical wing. I say wing, although I would really prefer call it a sail since it performs the duty of a sail on a yacht rather than the wing on an aircraft. Aerostat-01.jpg I can see that you could use a bridle attached at ...
by John Perry
Tue Feb 12, 2019 6:38 pm
Forum: Events & other announcements
Topic: AYRS meeting at the Basingstoke Canal Centre - 21 & 22 September 2019
Replies: 2
Views: 1072

AYRS meeting at the Basingstoke Canal Centre - 21 & 22 September 2019

All are invited to this weekend event in Surrey and If you cannot attend the whole weekend you are welcome to drop in for any part of the event. The Basingstoke canal is a very pretty stretch of water but it is not really suitable for sailing since there are low bridges and overhanging trees. Many A...
by John Perry
Tue Feb 12, 2019 11:21 am
Forum: Boats
Topic: AC75 Class Rule
Replies: 0
Views: 1365

AC75 Class Rule

The class rule for the boats that will be raced in the next America's Cup is now in the public domanin - could be te most complicated yacht class rule ever! Click here: AC75_Class_Rule v1.1 29 June 2018.pdf Would anyone care to predict which will be fastest - an AC75 or the F50 catamaran which is de...
by John Perry
Wed Feb 06, 2019 9:00 am
Forum: Boats
Topic: Press release: AC50 catamaran will do 20mph SOG against a 10mph tide in zero wind?
Replies: 2
Views: 801

Re: Press release: AC50 catamaran will do 20mph SOG against a 10mph tide in zero wind?

I don't think there is enough public domain information about the aero and hydro dynamics of the current F50 catamarans for it to be possible to calculate whether or not this claim by Artemis Technologies is realistic. However, perhaps we can do some guesswork analysis to at least get an idea. Doing...
by John Perry
Wed Jan 16, 2019 10:44 am
Forum: Sails & Aerodynamics
Topic: Request for collaboration
Replies: 18
Views: 5964

Re: Request for collaboration

Hi Robert, Sorry you lost your typing, this reminds me that when writing more than a few words to an internet forum it is best to first enter the text into a separate app then copy and past it to the forum website! I like to use the free Notepad++ app for that kind of thing, I find it much better th...
by John Perry
Fri Dec 21, 2018 6:47 pm
Forum: Sails & Aerodynamics
Topic: Request for collaboration
Replies: 18
Views: 5964

Re: Request for collaboration

Just one further point: I recall that when Didier Costes last attended a meeting of the AYRS, which was quite a few years ago now, I clearly remember him saying that the best lift to drag ratio of an airship hull used as an aerofoil is about 4:1. Perhaps this one piece of information might enable yo...
by John Perry
Fri Dec 21, 2018 1:54 pm
Forum: Sails & Aerodynamics
Topic: Request for collaboration
Replies: 18
Views: 5964

Re: Request for collaboration

Robert Biegler wrote: That is what I expect for an aerostat straight downwind of the anchor point, whose angle of attack is determined by the attachment point below the envelope, at least once there is enough wind that you can neglect the effect of buoyancy. If the aerostat has a wing attached to th...
by John Perry
Thu Dec 20, 2018 12:53 pm
Forum: Sails & Aerodynamics
Topic: Request for collaboration
Replies: 18
Views: 5964

Re: Request for collaboration

Rober Biegler wrote: Is anyone interested in getting involved? Yes, I am always interested in helping with other members projects and have done on a number of occasions in the past. One that springs to mind is the series of paravanes that I constructed for Slade Penoyre, past Treasurer of AYRS. The ...
by John Perry
Wed Dec 19, 2018 11:13 pm
Forum: Sails & Aerodynamics
Topic: Request for collaboration
Replies: 18
Views: 5964

Re: Request for collaboration

Not in either individual beam. And my understanding was that the torsional strength of individual beams makes a negligible contribution to the torsional stiffness of the whole structure. Robert, I guess that what you meant to say is the the torsional strength of individual beams makes a negligible ...
by John Perry
Wed Dec 19, 2018 8:37 pm
Forum: Hydrofoils
Topic: Trifoiler-style foils on IMOCAs?
Replies: 6
Views: 2140

Re: Trifoiler-style foils on IMOCAs?

I have just edited my post above since looking at it again I see that something I said is not right. I said that the foil should be adjusted so that its lift to drag ratio tracks that of the hull, or words to that effect. This is clearly wrong since for it to be worth using the foil, the lift to dra...
by John Perry
Sat Dec 15, 2018 1:00 pm
Forum: Hydrofoils
Topic: Trifoiler-style foils on IMOCAs?
Replies: 6
Views: 2140

Re: Trifoiler-style foils on IMOCAs?

I am not convinced that a constant angle of attack, perhaps at optiumum L/D of the foil, is best, because that neglects that at low speed, hulls can carry weight with less drag, and at high speed, a slightly higher angle of attack might still pay off by lifting the hull further out of the water, an...
by John Perry
Thu Dec 13, 2018 3:05 pm
Forum: Sails & Aerodynamics
Topic: Request for collaboration
Replies: 18
Views: 5964

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...
by John Perry
Thu Dec 13, 2018 12:46 pm
Forum: Sails & Aerodynamics
Topic: Request for collaboration
Replies: 18
Views: 5964

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). Zeppy 2 was an amazing project to cross the Atlantic ocean using an airship connected to a hapa (paravane) with pedal powered airscrew as a second means of propulsion. Th...
by John Perry
Sun Nov 18, 2018 5:17 pm
Forum: Hulls & Keels
Topic: Constant Camber (tm)
Replies: 4
Views: 1285

Re: Constant Camber (tm)

Have no personal experience but my freind Simon attended one of the AYRS meetings we held in Devon a few years back and he told us all about how he and his friend Andy built a 10m catamaran using the 'cylynder mold' method. Basically he hated that method of boat building and wished that he had built...
by John Perry
Sun Nov 18, 2018 4:38 pm
Forum: Hydrofoils
Topic: Trifoiler-style foils on IMOCAs?
Replies: 6
Views: 2140

Re: Trifoiler-style foils on IMOCAs?

When you mentioned the Trifoiler I somehow had the idea that you were talking about the Rave Windrider trimaran which I think was the same vintage, not the Hobie product that I think was a production version of the Longshot record holder - sorry about that. Thinking about this again, I think there i...
by John Perry
Wed Nov 07, 2018 10:55 am
Forum: Events & other announcements
Topic: Thorpe Meeting Novenmber4th
Replies: 1
Views: 870

Re: Thorpe Meeting Novenmber4th

I thought we had a good meeting on Sunday, significantly better attendance than this time last year. Thanks again to Fred and Margaret for making it happen. As always there was no shortage of speakers to tell us about their current projects, it seems that quite a few AYRS members are active in their...
by John Perry
Tue Nov 06, 2018 2:56 pm
Forum: Hydrofoils
Topic: Trifoiler-style foils on IMOCAs?
Replies: 6
Views: 2140

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) to a 'wand' that senses height above water surface? If that is what you mean, then I am not sure it would be allowed under the current IMOCA class rules (2018). Rule C.7.1(e) sa...
by John Perry
Tue Nov 06, 2018 2:14 pm
Forum: Miscellaneous Craft
Topic: Microtransat
Replies: 3
Views: 1614

Re: Microtransat

The link below is one of several papers about ocean research work carried out using SB-MET. http://sailbuoy.no/files/Report_Ekofisk_Nov2015.pdf The author does not go into detail about how SB-MET navigates itself, the main purpose of the paper being to discuss the capability of SB-Met to carry out w...
by John Perry
Mon Oct 22, 2018 10:17 am
Forum: Hulls & Keels
Topic: Hull impact resistance
Replies: 4
Views: 1619

Re: Hull impact resistance

https://www.facebook.com/BBCArchive/videos/489313454775023/ I just came accross the above link - a fascinating promotional film from the early days of glass fibre boat building. Just look at the clothing worn, both afloat and while laying up glass fibre in the workshop! Relevant here since it does s...
by John Perry
Sat Oct 20, 2018 11:04 am
Forum: Hulls & Keels
Topic: Hull impact resistance
Replies: 4
Views: 1619

Re: Hull impact resistance

Maybe better to ensure the hull has compartmentation and/or bouyant material sufficient that a puncture does not matter too much. So, although its a rather academic question, what hull material does have the best specific puncture resistance, i.e. for a given weight of panel, what kind of panel will...
by John Perry
Thu Oct 11, 2018 8:47 pm
Forum: Gossip & other snippets
Topic: Trailers, a warning
Replies: 2
Views: 2988

Re: Trailers, a warning

Well, my trailer maintanance may not be perfect but I hope that neither myself nor any other AYRS member would let their trailer get into that state! I find that with the type of suspension shown in that picture there is a tendancy for the wheels to splay outwards when the trailer is loaded - i.e. t...
by John Perry
Thu Oct 11, 2018 8:37 pm
Forum: Technical Papers for review and comment
Topic: Kasala latest news: crutches’ corner
Replies: 12
Views: 6171

Re: Kasala latest news: crutches’ corner

Josephine and myself have had a very good sailing summer, in Croatia, Italy, France and in the past month within our home waters around Plymouth UK. So I havent had much chance to look at internet forums, including this one. But now we are back on land its good to see that you have made great progre...
by John Perry
Thu Oct 11, 2018 8:11 pm
Forum: Miscellaneous Craft
Topic: Microtransat
Replies: 3
Views: 1614

Re: Microtransat

Well done the Norwegians, is the AYRS team (Mike Howard et al) still interested in this challenge. Still possible to do it faster! I took a look at the Norwegian teams website http://sailbuoy.no/. It would seem that they have a simple design, the rudder being the only actuated control surface. Hence...
by John Perry
Tue Jun 19, 2018 2:54 pm
Forum: Technical Papers for review and comment
Topic: Kasala latest news: crutches’ corner
Replies: 12
Views: 6171

Re: Kasala latest news: crutches’ corner

Hi Alex A delayed reply since Josephine and I have been sailing along the coast of croatia in our sailing dinghy so not much opportunity for looking at internet. Yes, pushing might work, or perhaps towing from a pole extending from the side of the towing boat. We will try again some time. John Perry 8
by John Perry
Thu May 31, 2018 7:19 am
Forum: Technical Papers for review and comment
Topic: Kasala latest news: crutches’ corner
Replies: 12
Views: 6171

Re: Kasala latest news: crutches’ corner

Alex - Here is another one that also has twin masts rotating in a circle! - http://www.mathisruhl.com/P-WM70T.html
by John Perry
Wed May 30, 2018 10:19 am
Forum: Technical Papers for review and comment
Topic: Kasala latest news: crutches’ corner
Replies: 12
Views: 6171

Re: Kasala latest news: crutches’ corner

hi Alex - yes I would be interested to read about Croseck's experiments. The books you mention are available second hand from various websites but it would be convenient for me if you could email the study to me as you sugest. j_perry@btinternet.com. Thanks. Regarding your proposal to tow your boat ...
by John Perry
Mon May 28, 2018 12:30 pm
Forum: Technical Papers for review and comment
Topic: Kasala latest news: crutches’ corner
Replies: 12
Views: 6171

Re: Kasala latest news: crutches’ corner

OK, fair enough, the polar diagrams included in your article are just an idea of the performance you would like to achieve and (with tongue in cheek), since you don't have any units on the graphs I am sure the boat will achieve the performance you are looking for! But seriously, it looks as though y...
by John Perry
Sat May 26, 2018 10:17 am
Forum: Events & other announcements
Topic: Speedweek Trials
Replies: 4
Views: 1838

Re: Speedweek Trials

Salvage - Sorry if you did not get a response in time, although maybe you did by private message. Yes, it did go ahead although with only a few people present. I went along for one day to see what was happening. On the day I was there Fred tried for the first time a small simple wingsail that he has...
by John Perry
Wed Apr 25, 2018 11:57 am
Forum: Technical Papers for review and comment
Topic: Kasala latest news: crutches’ corner
Replies: 12
Views: 6171

Re: Kasala latest news: crutches’ corner

Hi Alex I read your article about the 'Kasala' project in the current AYRS newsletter. It does look to be a very nicely built boat and I look forward to hearing about a successful launch - it seems that you have done nearly all the work and just need to buy some sails and bolt on a few off the shelf...
by John Perry
Fri Apr 20, 2018 11:01 pm
Forum: Boats
Topic: MicroTransat
Replies: 21
Views: 10305

Re: MicroTransat

A nice one at this link: http://www.bbc.co.uk/news/uk-scotland-n ... d-43838985
Doing quite well considering!
[img]
_97671573_ship2.jpg
(59.21 KiB) Downloaded 2835 times
[/img]
by John Perry
Tue Mar 20, 2018 6:28 pm
Forum: Boats
Topic: MicroTransat
Replies: 21
Views: 10305

Re: MicroTransat

Hi Mike, I expect that the AYRS membership would be interested to hear more about your design and your progress through this Forum and/or through AYRS publications so I hope that at some stage you will feel able to tell us more.
by John Perry
Thu Mar 15, 2018 6:22 pm
Forum: Boats
Topic: MicroTransat
Replies: 21
Views: 10305

Re: MicroTransat

Hi Mike Best wishes for your project, its good to hear that you have thought everything out really thouroghly. Just a quick comment on your comment that a water pump would just not be viable because of its power consumption. A very quick google search turned up this small pump, but there may well be...
by John Perry
Thu Feb 08, 2018 5:51 pm
Forum: Boats
Topic: MicroTransat
Replies: 21
Views: 10305

Re: MicroTransat

The Saildrone people now seem to have a whole fleet of autonomous model yachts roaming the oceans. Here are a couple of links:

http://saildrone.com/
https://newatlas.com/saildrones-csiro/53117/ - this one also has a mention of the clever 'Waveglyder' wave powered autonomous vessel.
John
by John Perry
Tue Jan 23, 2018 5:48 pm
Forum: Boats
Topic: MicroTransat
Replies: 21
Views: 10305

Re: MicroTransat

I attended the AYRS meeting at Thorpe (Surrey UK) on Saturday and at this meeting Richard Walker gave an excellent presentation of the team's approach to meeting this challenge - they have definitely put a lot of thought into this and should very soon be ready to start basic testing of prototypes, a...
by John Perry
Thu Dec 07, 2017 11:50 pm
Forum: Wind- & Water-turbines, Propellors
Topic: Yullah WAS Fishwics Brief Bio
Replies: 1
Views: 1503

Re: Yullah WAS Fishwics Brief Bio

Hi Mike I am not the 'webmaster'here, nor do I no much about the design of yulohs, but since no one else has answered your questions I will try: Q1) - you seem to have appended your post to a post by Simon Fishwick in the section intended for new forum contributors to tell people a bit about themsel...
by John Perry
Tue Dec 05, 2017 9:04 pm
Forum: Events & other announcements
Topic: Royal Institute of Navigation Meetings
Replies: 1
Views: 1683

Re: Royal Institute of Navigation Meetings

Did anyone get to the RIN lecture that Simon mentioned in the previous post? Is there any progress on any AYRS project in this area?
John
by John Perry
Tue Dec 05, 2017 8:54 pm
Forum: Hydrofoils
Topic: Sonic tubes
Replies: 1
Views: 1982

Re: Sonic tubes

Having just watched the part of the video that you refer to I have to say that this sounds suspiciously like an attempt to impress the viewer with scientific sounding waffle! If the presenter believes that the 'sonic tube' design provides a performance benefit then why does he not present data to su...
by John Perry
Wed Sep 06, 2017 4:59 pm
Forum: Technical Papers for review and comment
Topic: Howard Fund
Replies: 23
Views: 11044

Re: Howard Fund

Hi Alex - your workmanship, as evidenced by your photographs, looks superb! One point I would make with regard to keel section is that I think you need to consider the situation when the wind is strong, the boat is trying to go to windward so keel loading is high but speed through the water is very ...
by John Perry
Tue Jan 24, 2017 10:39 am
Forum: Events & other announcements
Topic: AYRS Devon Meeting - CHANGE OF DATE - 1st April 2017
Replies: 0
Views: 2176

AYRS Devon Meeting - CHANGE OF DATE - 1st April 2017

We have changed the date for our AYRS Devon meeting to Saturday 1st April 2017. The reason is that the original date did not suit a couple of our local members. I realise that we cannot choose dates to suit everbody but the numbers attending these meetings have never been large, so the absence or pr...
by John Perry
Wed Nov 09, 2016 1:51 pm
Forum: Events & other announcements
Topic: AYRS Devon meeting - Saturday 11th March 2017
Replies: 0
Views: 2453

AYRS Devon meeting - Saturday 11th March 2017

The exact location for this meeting will depend on the level of interest. In past years the meeting has been held in John and Josephine's house at Wembury, a coastal village about six miles to the south east of the centre of Plymouth. This will probably be the location for our meeting in 2017, unles...