Mental Health & Wellbeing Volunteers [Pinned]

In SA it's winter around the corner and at the rate they are vaccinating might be 2022!

1 hour ago by 🇿🇦 Ianh ( Commander)

General Resources

Clinker ships boats.

One I did earlier just like Blue Peter. Keel joined & setup on jig.

1 hour ago by 🇬🇧 hammer ( Sub-Lieutenant)

Building Related

RN DARK CLASS

Rowen, I have sent my files twice, the last time in multiple message format. Could they be hiding in your Spam folder? Jonathan

2 hours ago by 🇺🇸 ToraDog ( Warrant Officer)

Building Related

Police boats

The boats look like ex Raf, tenders, or ex RN motor launches

5 hours ago by 🇬🇧 jarvo ( Lieutenant)

Hobby Chit Chat

Americas' Cup, a bit of good news

The Prada Cup to decide who races against the defending champions is over. Were we robbed? Our boat favoured the stronger breezes but it was not to be. So the Red Moon is triumphant and probably deservedly so.. The New Zealand team although lacking match race time have been watching carefully. They have been racing when ever possible. As ever, exploitation of the rules can lead a design idea down a nearly parallel path but.... In the case of the NZ boat if you look at the deck it is 18 inches lower than the other yachts. Beneath the deck below the mainsail the other yachts have put the mainsail hydraulics to clean up the design. NZ have not done this, they have put all the mainsail hydraulics in the mainsail boom, looks a bit ugly having the bits on show but it was done with a reason. As this space under the deck is now redundant the deck has been lowered and this means the sail continues down to deck level giving an extra 18 inches of sail depth and when multiplied by the sail length is a considerable area, but legal! It has another advantage as well, as it lowers the centre of effort of the sail and so for the same wind pressure she can stay upright for longer. Another thing team NZ have done is that they do not lower the leeward foil quite as much, pushing the balancing point of the foil just 4 inches further out from the centre of the yacht. N.B. the fulcrum of the foil mechanism is not on the centre line of the boat. The effect of this is a bit like lowering the lead further down on a keel yacht so making it stay more upright and stable. Now 4 inches about 20 feet out, is not a lot, but the weight of the boat acts upon this point so it has to be multiplied by the 7 1/2 tons of boat! These two innovations for a given wind speeds give a 7 1/2 % advantage in speed. Back in the day of the big monohull yachts half of 1% would give you victory! The rounding of the gates is getting more sophisticated for all. There are trim tabs on the rudder foil acting a bit like the elevators on an aircraft. There are similar tabs on the main foils a bit like the ailerons etc. However on an aircraft they bank into a turn, this would be disasterous on the AC 75 yachts. They need to stay flat, so the foil 'ailerons' are used in the opposite way, this keeps the hull level. The elevator on the rudder is used to slightly dip the bow and lower the hull when rounding the gates this is to ensure when turning that the bow does not rise should the wind speed suddenly increase. Well that is what we are told! Just watch what they do! So this maybe a one horse race but Luna Rossa will be well aware of the NZ boat and its capabilities and probably has a few tricks left yet to play. I watched a practice start and 4 lap race and Team NZ just sailed away from them. Or did they? Tactics are very much the name of the game in match racing. Should the Team NZ win the Americas Cup it is almost certain that the races for 2025 will be held elsewhere. This leads on to thinking where this might be? As for example should it be in European waters then the North Sea presents a far different environment with short steep seas against sailing off the Americas. Aukland has relatively sheltered waters and there are 8 race areas, chosen partly depending on the wind direction, basically it has to blow down the course forcing tacking manoeuvres. One Prada race was called off as the wind veered 90 degrees and then it becomes a straight speed test on a beam reach. Designs would be different, this current design was a logical development of the AC72's of 2017. They were catamarans with foils but one hull was always redundant as they changed tack, and the crew moved across the hull, but it still took a genius to work this out and come up with the AC75's. If you want to see for yourself, the above is an evenings You Tube watching. Try, americacup.com, Planetsail (v.g.) Mozzy Sails, very technical. The Americas Cup starts on the 10th. March a delay due to some local covid infections and may still need special government permission to commence the racing. regards Roy

6 hours ago by 🇬🇧 roycv ( Petty Officer 1st Class)

Non-Hobby Chat