Tuesday, 12 May 2015

Stainless steel rods?

Well, I did it again.
Once again I asked the CEO of Portabote about the flexing transom.

I sent an email off to Sandy Kaye, asking him if he could tell me why they allow a flexing transom.
I also sent a number of possibilities as to why this could be the case.
These possibilities are:

1. Safety. Because you have to angle the outboard, optimum performance cannot be achieved as stated by a few forum members and this will limit maximum speed. (I have experienced this myself in that my 10’ bote goes a lot better if the outboard is vertical, it just hits the back of the bote.)

2. It has become necessary to have a thinner transom to accommodate the folding transom.

3. It’s just a side effect of having a plastic transom and now a thin metal one.

4. Cost. You are trying to keep the cost down as much as possible for your customers.

5. Weight of the bote to be kept to a minimum.

I was pleased to receive a reply almost immediately and this is what he said:

“Thank you Matt,
You stated a lot of the correct answers yourself.
I wish you had a chance to actually use the Bote with the folding transom. It flexes when you start. But then the vertical stainless steel rods help to rigidify it pretty well.
We have quite a few out there now and people seem to be satisfied with the performance.
The picture that I sent you does show how well it performs.
Thank you again for asking these good questions.


Having read his reply, I have a couple of concerns.
I don't how effective the stainless steel rods (which are used to keep the transom folded. There are two of them) would be as they are about the size of small tent pegs.
In any case, they couldn't be very strong, strong enough to prevent flex anyway or to have much effect..
Sandy's reply also suggests that there are other reasons that are not mentioned.

The question was also raised again in the forum in regard to maximum safe  speed for the new Alpha series bote.

In response Sandy re-iterated that the maximum safe speed for the Alpha series would be about 15mph (about 13 knots or 24 kph), after which the hull begins to spread at the sides and becomes a little unstable.

This spreading hull has become known as "flexisplay", a term coined by Paul from "The floating log" blog.

Sandy has also recommended that when using a 9.8hp on the 14' Alpha series you should limit speed to a little over half throttle and went on to say that any more than that would be of no value due to maximum hull speed and it is a waste of fuel.

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