[C320-list] Prop Info

[Bob & Bel Harrison]

I suspected that my tach reading might not be accurate, so I had a mechanic
check it, and he said that it was okay. He didn't give me an absolute
accuracy figure though.  Since the tach reads from the alternator, and we
have the high-output alternator, it wouldn't have been too surprising if the
reading was off.
As far as the speed measurements go, I did them to compare the relative
motoring speed of the two props.  7 knots for a 15x11 versus 6 knots for a
15x9 also sounds reasonable to me.

We don't have an electronic wind system on the boat, so sailing speed
relative to wind speed is a subjective judgement.  For the last couple of
years we have had a pair of eagles that sit on the mastheads and destroy the
anemometers & wind indicators, so to save ourselves the trouble we didn't
have a system put in. Fortunately for us, unfortunately for them, they're
not around this year (likely shot by poachers), so it's worth considering
again.
Does anyone have experience with the TackTick systems?
http://www.tacktick.com/products/product_view.asp?prod=35
Wireless, solar-powered, sounds pretty easy to install....

Bob Harrison


-----Original Message-----
From: c320-list-bounces at catalina320.com
[mailto:c320-list-bounces at catalina320.com] On Behalf Of Len
Sent: Tuesday, November 07, 2006 10:24 AM
To: C320-List
Subject: Re: [C320-list] Prop Info

Re Maverick---Have you checked your engine rpms with photo tachometer?  I
found indicated rpms about 250 rpm below actual; will recalibrate soon.
Also, at max throttle 3600 actual, my boat does 7 knots (per gps sog) with
standard factory 3-blade 15x*11*.

Len Krane
Aqua5   #1070.


On 11/7/06, Bob & Bel Harrison <b_harrison at shaw.ca> wrote:
>
> Earlier this year we installed a 15" Three Blade Classic Max-prop to
> replace
> a 15x9 3-blade fixed prop.
> Engine is a Yanmar 3YM30, standard transmission.
> The prop was set to the manufacturer-recommended 10.3 (20 degrees) pitch,
> and here are some before & after boat speed measurements...
>
> RPM   Fixed   Max-prop
> 2300    4.4    4.6
> 2600    4.85   5.13
> 2900    5.35   5.65
> 3200    5.8    5.95
> 3500    6.0    6.28
>
> It seems to me that since the engine has no difficulty reaching high RPMs,
> the prop could be pitched a little higher, say 11.4 (22 degrees).  I'm
> considering changing it at next spring's haul-out, but on the other hand,
> why mess with something that's quite satisfactory?
>
> Bob Harrison
> Maverick #1007
>
>
> -----Original Message-----
> From: c320-list-bounces at catalina320.com
> [mailto:c320-list-bounces at catalina320.com] On Behalf Of Jeff Church
> Sent: November 6, 2006 11:06 AM
> To: C320
> Subject: [C320-list] Prop Info
>
> The boats on the hard and I'm working thru my winter project list. I'm
> about
> to re-pitch my MaxProp and I'd like to know what pitch other 320 owners
> are
> using. MaxProp's database is out of date. They only list the C320 with a
> Perkins diesel.
>
> If you have a MaxProp and a Yanmar please let me know the pitch,
> transmission ratio, and your maximum speed and RPM while motoring.
>
> Aside from taking the results into account for my use, I'll update MaxProp
> with the information.
>
> Thanks
>
> JeffC
>
>
>