[hpv-boats] Nauticraft Drive Unit availability

[Curtis Chambers]

Hello Everyone,

In response to David Adrian's interest in drive units we have some used
Nauticraft drive units for sale - ranging from $200 to $500 - shipping not
included of course. (Our new ones are $650.)  These units would include our
15 in.  (385mm) two blade propeller (custom injection molded for us) but no
drive shaft (we now use 3/4"  acetal (POM) rod for the Escapade but support
it in several places; our Encore has 1 1/8" od aluminum tubing shafts).  A
3/4" diameter seal/bushing is also included.  The ratio is 1:4 (21: 84 tooth
sprockets).  Keep in mind that our drive system is designed for recreational
boat use - not ultimate performance.  Contact myself or Laurie.

Curt Chambers
Nauticraft Corp.  

-----Original Message-----
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Sent: Saturday, November 27, 2010 3:00 PM
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Subject: hpv-boats Digest, Vol 66, Issue 3

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Today's Topics:

   1. Re: Gearbox (Rick Willoughby)


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Message: 1
Date: Sat, 27 Nov 2010 08:43:33 +1100
From: Rick Willoughby <rickwill at bigpond.net.au>
Subject: Re: [hpv-boats] Gearbox
To: HPV Boat <hpv-boats at bikelist.org>
Message-ID: <7E79E6C8-49A9-40F8-BD68-C426F965ED59 at bigpond.net.au>
Content-Type: text/plain;	charset=WINDOWS-1252;	delsp=yes;
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David
The box I have made could only be regarded as a prototype. I use standard
size aluminium flat and round to make it.  It is held together with
stainless bolts.  It took about 8 hours of effort to produce it.

A friend here is investigating having the casing cast.  This is some time
off though as I am still playing around with other ideas for the gearing.

I have been working with Mitrpak but they can only make a 1:2 ratio at this
stage.

I also have an Involute gearbox that has a 1:3.3 ratio.  George Tatum
arranged for their manufacture in India.  I think George still has some and
both Ian Cassell and I bought ours from India in the last few years.  These
cost less than  the gears would cost to buy  
elsewhere.   Involute may be able to produce something in small  
quantity with 1:4 or higher ratio.

The Involute boxes weigh 3.8kg which is quite heavy but they are
tremendously strong.  I expect the shafts would shear before the gears fail.
The gears I used are good for peak power somewhere over 500W in normal boat
application but a strong cyclist can exceed this quite easily.  I have been
told sprint cyclist can shear standard shafts.

Rick

Hello Rick,

As always your writing is quite interesting.
As you know, I am working on a human power rotomolded kayak project with a
rigid shaft directly set on the gearbox.
As the propeller is located below, and protected by 2 keels, it is not
possible to set a big propeller, that?s why I tend to put a 1:4 box and an
average size prop (rather 340 mm in my case).
I currently build myself this box for the time being but it is difficult and
time consuming. That?s why I would be enthusiastic to be able to buy one.
Would you have some pictures of your 1:4 box and an idea of its selling
price if ever?

Many thanks, David,



Best regards,

David Adrian




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