[hpv-boats] V15 Shaft

[bruceplazyk at fauxfishtechnologies.com]

Hi Rick,

It's great to see that you are still pushing the envelope! That's a great looking boat.

Bruce Plazyk

--- On Sat, 8/14/10, Rick Willoughby <rickwill at bigpond.net.au> wrote:

From: Rick Willoughby <rickwill at bigpond.net.au>
Subject: [hpv-boats] V15 Shaft
To: "HPV Boat" <hpv-boats at bikelist.org>
Date: Saturday, August 14, 2010, 5:23 PM

Vic
I tried the 6mm sleeve I had on a 1/4" spring steel shaft.  I was disappointed because it did not make measurable increase in the torsional rigidity.  It is an effective way to protect the shaft.  When I tested it the epoxy was only a couple of days old so not fully cured.  I will do a more precise side-by-side comparison with unsleeved rod at some point.

As Mark Drela commented it would have been smarter to use thicker tube.  It is much easier to reduce the diameter of the tube by pulling it tight than it is to increase the diameter when it is loose.  The fibes in the sleeve are running more like 20 to 30 degrees than 45.

The new shaft is a combination 12mm aluminium rod through a HDPE pipe in the hull and 8mm spring steel beyond the tube.  The steel portion slots into the aluminium.  That connection is epoxy glued and I have wrapped a few layers of glass tape over the joint.  I made a small sleeve from UHMWPE for the bearing at the bottom of the shaft tube.  The tube exits just behind the gearbox so it does not need to be sealed.

The folding prop sheds most weed so I do not need access to it.  It is possible to get a bit of weed wrapped around the hub but that will usually dislodge by reversing.  Most floating weed gets pushed aside by the hull.

Having the prop right out the stern reduced the tendency to ventilate in waves.  This improves as I go faster because the boat sits bow up a little and the prop goes deeper.  In the 1 to 2 ft waves yesterday the prop only ventilated a couple of times.  The side mounted prop would have ventilated more often in waves like that.

Rick

On anothe note, wonder if you ever got the time to test out the idea of a
carbon fiber sleeve reinforcement on your flex shaft?
http://www.cstsales.com/carbon_braid.html  I haven't had free time to
explore this yet.

Regards,

Vic


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