[Public-List] Propellers...

[George Dinwiddie via Public-List]

Sounds like a complete win, Gord.

On 6/5/16 10:42 AM, Gordon Laco via Public-List wrote:
> Hello friends,
>
> I¹m sorry to reintroduce this topic... But I¹ve changed propellers and
> thought I¹d share the experience.
>
> Some of you may recall that I have pontificated about taking a Œdon¹t
> change¹ position with regard to the prop supplied by Whitby Boatworks with
> the Atomic IV engines many of our boats have.
>
> Well this spring I was thinking about the engine and decided to try a
> change.  Last fall¹s ŒMisery Trip¹ reached a crescendo of suffering with a
> slog to windward in 40 knot winds and a sharp chop...  We were nearly
> stopped a few times, mostly by wave action, but SURPRISE trudged along and I
> would say coped better than our companion¹s boats which were all fin keeled
> yachts fitted with diesels.    So power delivered to the water wasn¹t the
> issue... What I was thinking about was alternator performance and cooling.
>
> Cooling has never been an issue with our engine, particularly since I
> replaced the old water pump with the upgrade offered by Moyer.  However I¹ve
> been keenly aware that our cruising RPM of about 1000 doesn¹t really spin
> things down in the engine compartment fast enough to deliver what the
> alternator is theoretically capable of.
>
> I liked the look of the narrowed bladed ŒCampbell¹ props I¹d seen on other
> boats, and liked the idea of increasing revs while at least keeping the same
> Œpower in the water¹ situation the stock two bladed prop gave us.  So I
> ordered the Campbell which they recommend for Alberg 30¹s fitted with Atomic
> IV engines with 1:1 transmissions.    The vendor said he was certain what
> shaft diameter and taper my boat has... But because I¹m a doubter, I sent
> him my old prop for reference.
>
> In due course the new prop came back along with the old one (and he was
> right, he did already know the specs).  I couldn¹t wait to try it out.
>
> We installed the new prop as part of my condensed spring outfitting (and no,
> I did not do the cap rail job I wrote about earlier.  I got busy with work
> which took me away most of April and May so that¹s that on that job for
> now).  Eagle eyed Rod saw the shiny new thing and commented ŒI thought you
> said...¹     Well I know what I said, but what the heck...
>
> We got SURPRISE into the water and after securing the rig, started up and
> started the two hour trip back to our sailing club.  First thing I noticed
> was that I seemed to have a lot more power in reverse than before.  The
> second thing was that prop walk seemed to have dissappeared... Amazing.
>
> The only negative comment I¹d read about these props on line referred to a
> supposed loss of maneuvring power... But I was able to do the usual spin
> within her length that SURPRISE normally does.    Motoring out of
> Dutchman¹s Cove Marina, I found that our speed at idle was lower, and that¹s
> a good thing of course not unexpected because of the finer pitch.  Once out
> past the breakwater, we opened the throttle and both Caroline and I were
> amazed.  Boat speed climbed to 6.6 knots as usual for full throttle, but
> there was no roar and vibration from the engine.  I won¹t say it was as
> quiet as electric, but the change from how things were was startling and
> dramatic.   We were so quiet at full speed I mistrusted the knotmeter and
> fired up the GPS, but it confirmed the speed.  Amazing.
>
> We found our old cruising speed of 5.2 at 1000rpm was now 5.2 at 1400 (this
> second RPM was full out open throttle with the old prop). Yes the engine was
> spinning faster, but at the same throttle setting and clearly not labouring
> quite so hard.   The boat was so quiet we didn¹t feel like we were moving,
> so we did the trip at 6+.
>
> So the prop change is rated a total success.  But there was a surprise in
> store for us.  Because I was away so much I didn¹t do my usual thorough
> recharge of the batteries... We started up after launch on what was left in
> the batteries after the Misery Trip and months of winter lay up.   I was
> glad there seemed to be enough juice to spin the engine.
> Yesterday I decided to connect up the battery charger and run it all day...
> But after only moments, the charger was indicating full charge.  I assumed a
> problem with the charger but after investigating, realized that the
> Œproblem¹ was that the battery bank was indeed fully charged and the
> automatic function on the charger was sensing this and shutting off.
>
> How could that be, I thought... Then it occurred to me that the alternator
> must have run up the batteries on the trip over from the marina.  In the old
> days, the alternator barely kept up with the engine¹s requirements and I¹d
> had to charge from shore power periodically.  So it appears that whatever
> was in the batteries at launch, the engine itself topped them up in the 90
> minute shot over under power (wasn¹t two hours because we galloped home
> faster).
>
> Happy happy.
>
> Gord #426 Surprise

-- 
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   When I remember bygone days                         George Dinwiddie
   I think how evening follows morn;            gdinwiddie at alberg30.org
   So many I loved were not yet dead,           http://www.Alberg30.org
   So many I love were not yet born.                          also see:
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