[hpv-boats] Flex Shaft Material Selection (Dom Rumbolo)

[Dom Rumbolo]

Rick,

Thanks for the info, I ended up ordering the sewer rod.  Almost ready to
start building it.

I'm not sure how my surfski compares to the Epic V10, it's an older Valhalla
Victory I think.  You're right about the need for stabilizers; I had a tough
time keeping it upright while paddling in calm water.

That weight target will be a challenge, I estimate the boat weighs 16 kg
as-is.  Is the foremost issue transportability?

Thanks for the link to Mike Lampi's build, maybe I can learn something about
laying fiberglass there.

Dom

On Thu, Jun 16, 2011 at 3:30 PM, Rick Willoughby <rickwill at bigpond.net.au>wrote:

> Dominic
> The sewer rod is probably the better selection.  I have seen these rods in
> use and suspect they are spring steel but am not certain of this.  The end
> fittings are similar to what I have done with spring steel although with
>  5/16" diameter you do not need to be fancy if the connection is not seeing
> the bending stress.  Irrespective these end fittings give you something to
> work with for connecting to prop and gearbox.  So that is added value.  I
> have paid $60 for a single connector before I started making my own.
>
> Assuming they are spring steel then you should aim to arrange with at least
> 3.5m radius curve.  For the 1.8m length you can drop 0.5m.  The prop shaft
> will need to be around 250mm below the surface so the gearbox cannot be any
> higher than 250mm above the surface.  This should be easily achievable with
> a surf ski.  The output shaft on the gearbox will angle down at 30 degrees.
>  If you can get the gearbox closer to the water then that is even better.
>  Obviously the down angle of the shaft will reduce in this case.
>
> The surfski should be a good platform.  I have modelled an Epic V10 hull to
> check performance and they are a slick hull.  If you have something similar
> it will go well.  You will not operate it reliably without stabilisers - CoG
> will be too high.  For smooth water operation you can have stabilisers mid
> mounted.  If you want to operate in waves then mount them toward the stern
> to reduce flop roll.  Use two not one.  They need to be long and slender
> with a volume at least 15 litres.
>
> The 5/16" shaft with 16X16 prop will have very good feel - similar to
> riding a bike.  With the 1:2 box you will need around 1:3.5 in the chain.
>  This is a nice ratio as you can use mountain bike stuff.   You can side
> mount the prop so it can be reached for cleaning.  The shaft strut will need
> to be stiff enough to prevent the prop from hitting the hull when you turn.
>
> From a practical use point of view, weight is really critical.  You should
> make an estimate of weight.  Count every nut and washer.  Make allowance for
> paint.  You should target 20kg or less.
>
> As a matter of interest Mike Lampi launched his V15-6m last weekend:
> http://hpb-er.blogspot.com/
> He has some minor issues to sort but it went well for first time out.
>
> I plan to give my V15-6m its first run this weekend.
>
> Rick
>
>  Date: Thu, 16 Jun 2011 07:46:06 -0700
>> From: Dom Rumbolo <drumbolo at gmail.com>
>> To: hpv-boats at hupi.org
>> Subject: [hpv-boats] Flex Shaft Material Selection
>> Message-ID: <BANLkTi=EAPZpGOmXKVALXQ+**C1bwpmYKeVg at mail.gmail.com<EAPZpGOmXKVALXQ%2BC1bwpmYKeVg at mail.gmail.com>
>> >
>> Content-Type: text/plain; charset=windows-1252
>>
>> Hi Rick and the rest of the list,
>>
>>
>>
>> First of all I?d like to thank you for your huge contribution to human
>> powered boating.  I?ve followed your threads around the Internet and it?s
>> been a great inspiration.
>>
>>
>>
>> I?m starting on my pedal-powered build, using a fiberglass surf ski as the
>> foundation.  I picked up a T-gearbox at 2:1, and plan to start with the
>> APC
>> 16x16 prop, a 5/16? steel flex shaft, and chain gearing.  As has been
>> mentioned, finding spring steel in the US is not easy.  Doing some
>> research
>> on the Internet, this is what I?ve come up with and I?d appreciate your
>> input:
>>
>>
>>
>> A search for spring steel yields several grades of steel, including 1095:
>> http://www.tmtco.com/products/**spring-steel.html<http://www.tmtco.com/products/spring-steel.html>
>>
>>
>>
>> Trying to find 1095 steel, I see that it is equivalent to W1 drill rod:
>> http://forums.dfoggknives.com/**index.php?showtopic=6783<http://forums.dfoggknives.com/index.php?showtopic=6783>
>>
>>
>>
>> Can?t find W1 drill rod in anything longer than 3?, but I see that A2
>> drill
>> rod is similar: http://www.onlinemetals.com/**toolsteelguide.cfm<http://www.onlinemetals.com/toolsteelguide.cfm>
>>
>>
>>
>> A2 drill rod is available in 6? length and fairly cheap:
>> http://www.mcmaster.com/#**8888k416/ <http://www.mcmaster.com/#8888k416/>$26 shipped
>>
>>
>>
>> Alternatively, flexible sewer rod is available:
>> http://www.flexmax.com/**maxlife/cat1.html<http://www.flexmax.com/maxlife/cat1.html>(MDA-72LC, powder coated) $41
>> shipped
>>
>>
>>
>> I?m not sure of the material properties of the sewer rod, but it is nice
>> that it comes powder coated.  Here is some data on A2 drill rod:
>> http://cartech.ides.com/**datasheet.aspx?i=103&e=262&c=**techart<http://cartech.ides.com/datasheet.aspx?i=103&e=262&c=techart>
>>
>>
>>
>> Thanks,
>>
>> Dominic
>>
>>
>>
>>
>
>
>
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