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Jackett

Member Since 27 Mar 2011
Online Last Active Today, 12:19 PM
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Posts I've Made

In Topic: foil assisted cruiser

10 February 2017 - 02:31 PM

What a bunch of negative comments, on a forum claiming 'anarchy' and where you all moan about average white blobs and all boats looking

the same . . .

 

Trunk cutting through the accommodation - its a 56 foot yacht with relatively high freeboard, so I'll image it will be below the sole.

 

Rattling in its trunk at anchor? Modern roller systems are pretty good at stopping that. And when not in use it fully retracts into the case - so its not being pushed around by the watter, so what's causing it to move around and rattle?

 

Uncomfortable motion? Well any lightweight, fast boat isn't exactly comfortable. But the DSS allows a narrower waterline as you're less reliant on form stability, which should help, plus the fin may act as a good damper. Certainly the reviews of DSS in Yachting World etc. all seem to comment on the DSS improving comfort. Anyway, I thought the consensus here is that most people are wimps who just sail from marina to marina in nice weather, so who cares about comfort in rough seas?

 

No, I've nothing to do with the company, never sailed a DSS equipped boat and it may well be a rubbish boat. But based on what experienced sailors who've sailed DSS equiped boats have to say maybe this is something to keep an eye on, maybe even raise a modicum of excitement?


In Topic: My newest project

18 January 2017 - 10:54 PM

I posted that last post around 1:30 am this morning. I went back to bed and thought, "Maybe the interior drawing for LOON is lost and that's why you never see it." But I found it in the tube with the other drawings this morning. It's nothing special but I will get it scanned and posted. Maybe not today. But early next week for sure. I am also looking for the drawings of the WHITE WING 36'er. This is one of my sweetest sailing designs and it is the first time I used a pipe frame sprit 38 years ago!

 

Bob,

 

Sorry, I've been separated from my computer for a while and only just checking back in. Did you get a chance to scan the accommodation drawing for Loon?

 

I got the 'Bluewaters Cruisers' book in my Christmas stocking after you mentioned it here. Some very nice designs of yours I'd not seen before. You're just going to have to do another book, to include all those drawings you didn't fit into the first!


In Topic: My newest project

23 December 2016 - 09:30 AM

Steve:

I thought of you yesterday when I saw that lead.

Here you go.

LOON%20construct_zpsaapxcvbt.jpg

 

I looked at those designs from Mellgren and he has about every rudder style covered including partial skegs, full shegs, barn doors and even one that looks exactly like a C&C scimitar profile and he did that in 1903! In fact he takes several  whacks at the scimitar shape. He really knew what was going with reducing the root chord. I had never heard of the guy until this morning. He is in the ENCYCLOPEDIA OF YACHT DESIGNERS.

 

While there is thread drift about Loon, do you have an accommodation plan handy? I've admired photos of Loon for years, as well as the drawings you've posted here, but don't think I've ever seen anything hinting at how the interior is arranged. Until seeing this construction plan I'd not realised the engine was so far forwards so now even more intrigued regarding the interior.


In Topic: Tumblehome?

14 November 2016 - 01:05 PM

French warship designers of the late XIX and early XX centuries seemed to love the tumble-home design... I think they expected it to be more efficient at deflecting enemy shells than a vertical side. Here you have some pictures of the pre-dreadnought battleship Tsesarevich, from the Imperial Russian Navy, but designed and built in France:

 

https://en.wikipedia...h1903France.jpg

 

1904_08_00_tsesarevich_at_port_arthur.jp

 

a6dabe84312c80804890a28d85e7ca30.jpg

 

 

 

Its commonly stated that the tumblehome was to help deflect shells up. This isn't the reason, or at least no the primary reason.

 

The limitations of the guns at the time (and the targeting apparatus) meant that the shells likely to hit the hull would be fired at fairly short range and so would have a fairly flat trajectory. 

 

If you had, say, 2 inches of armour and vertical topsides, the shell had to penetrate 2 inches of armour. But if that armour was raked at 45 degrees, the shell had to travel further to penetrate the armour as its travelling at an angle through the armour- just over 2.8 inches. So raking the armour has the effect of increasing the thickness of the armour (from the point of view of the shell) without any weight penalty (a weight saving potentially, as for a given waterline beam you ended up with less deck, which is itself more weight).

 

Its the same reason as armoured vehicles tend to have raked sides. The rake may help deflect the shell up, but that's not the primary reason for the rake.