[hpv-boats] V15 Shaft

[v garza]

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

> 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.


Was this shaft you constructed covered with only a single layer of carbon 
fiber mesh tube?
What kind of epoxy did you use, and did you use the heat shrink tubing 
method to tighten up to the shaft?

>
> 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.

Could that angle strength be improved somehow, say by using multiple layers 
set in offset mesh pattern, alternately reversed from a lengthwise 
direction?

Thanks,

Vic


>
> 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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