Wednesday, 13 January 2016

An enquiry from John in South Africa


Hi All

I still get quite a few enquiries about my proa experiences.

To save answering the same question time and again here's a common one. There has been much conjecture about my decisions to do this or that over the years, frequently answered by those who think they know what my motivations are better than I do!

Dear Harmen, sorry to intrude! 

I  have been reading your blog off and on for years, and recently spent a lot of time going over it again.
I was thinking what sort of boat I would make if I were to build a  beach/lagoon proa. 
When I went back further in your blog I found that your earlier boat, with the  Bermudan rig was very similar to what I had drawn, basically a smaller version of Jzerro.  The only major difference was in the positioning of the mast,
I was surprised to see that you had found this layout unsatisfactory, and moved to the Crabclaw sail and steering boards in Toroa.
Can you please explain to me what some of the major problems were with the earlier boat.  I can see that perhaps it was had a too high mast and main, and that with the mast position you used on the hull you would not have been able to stay off to lee at the bows like Russell Brown has done with his more windward   mast position.
Best wishes
John
 Cape Town

Hi John.

Nice to get a message from you.

I was not dissatisfied with the Rig of Takapu. It was the perfect amount of power for me. Bear in mind that the proa configuration gives you 50% more righting moment than a catamaran. If anything it was the most versatile and successful rig configuration for our sailing conditions in NZ.

I was not that impressed with the rudder solution required to balance and steer. The rudders were dual purpose, they were counterbalanced to act both as a centre board and rudder. This required a very strong stainless steel shaft which needed to be thick enough to support torsion and tension loading simultaneously. This thickness of shaft meant a heavy assembly a long way out at the ends of the hull combined with a thick rudder blade cord section to accommodate it. I went for 5/8" s/s rod. They eventually bent from multiple groundings and high leeway loading at speed.


Being centre case loaded cassettes, these rudders were the most unreliable aspect of the design. I had always wanted to try weight, trim steering as was traditional in Micronesia. To do that I decided to opt for the lateen rig. I was immediately sold on the rudderless steering idea. Mostly this required an experienced crew. As I was a loner and crew was nowhere to be found I let this evolve into an ogive section centreboard steering system which I describe in my dissertation.

If I was to start again I would modify the Takapu model and develop that. It was best for single handling particularly when I had two roller furling jibs, one at each end.


In answer to your question about the rig being taken aback and comparison to JZerro.

The mast was supported by a rigid windward compression strut so that it could not blow over to windward. The windward hull was just buoyant enough to support the load whilst I corrected the situation.

I very rarely got taken aback but when I did there was no issue with sailing the boat back out of trouble.

I am too unwell with RA to continue with my practice based proa research so I have resigned myself to sailing a small canoe and a 10 foot dinghy. I am still sailing solo except on the rare occasion when my children visit.

Hope this is helpful.

Best

Harmen



No comments:

Post a Comment