I have an older bcc (hull #14 - 1976). It has a 10hp Sabb diesel. With
a variable pitch prop. I have made all the easy adjustments, but
still not enough thrust in forward. The only thing left is to cut 1/2
inch off forward end of shaft which is frozen into collar and won’t
budge. Anyone with a suggestion I would appreciate any help.
Thanks, Larry Heitman (Dilkara)
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Larry:
We have a Sabb G engine - 10 hp. Please give me more details and I can probably help you.
In terms of propulsion, we normally motor at between 4 and 4.5 knots at 1,600 rpm. With a clean "bottom" and calm water we have seen 5 knots but 4 to 4.5 knots is normal. If this what you mean by "not enough thrust?"
Rod
S/V IDUNA
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Thanks Rod for the answer back.
When I put the prop in full reverse it creates a virtual rapids under
the hull. As I continue in reverse and put into full forward, the
boat will drift back for at least 10 seconds. A bit dangerous. Also
in any kind of heavy chop it will barely make way. So I think that it
needs fixing. I did see the same plant on another local boat, but the
prop was abotu 2 to 3 inches wider in diameter.
Thanks again Rod
Larry Heitman (Dilkara)
Rod - Thanks for the answer back.
When I put adj. prop in full reverse it creates a lot of wash under
hull. She will continue moving in reverse for l0 sec. or more before
finally heading forward. Also in a fairly heavy chop it will barely
make way. 4.5k is about max in calm water. My engine came with the
small prop dia. that Sabb can deliver with the 10 hp unit. This could
be the difference.
Thanks again, Larry (Dilkara)
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Larry:
Do you have the full feathering prop - GSP engine? If you have hauled the boat, did you check the pitch while the boat was on the hard? We have the G engine which just has the variable pitch prop - large prop.
I do not believe you can expect much more than 4.5 knots from the 10 hp engine. Based on our experience, 4.5 knots is making good time in a chop. Perhaps Waxwings and Calypso can add more to the discussion.
Fair Winds,
Rod
I have attached an image of the prop shaft. You may want to talk to Bill Miller of Sabb America - 888-301-1706 - toll free.
Rod
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Hello Rod & Larry,
Calypso has the Sabb GSP. We do about 4.8 kn in glass without towing a dink. Less in chop - depends on how much chop :}. I usually run with the pitch maxed out, unless I have a large alternator load, or compressor load. We have a refrig compressor on the engine. I do have an alternator field kill switch so that I can get maximum shaft hp when needed. In neutral, I find that the pitch lever is slightly forward of vertical, which I suspect is a good indicator that I could pitch the props a little more. I have not looked into what this would take - I suspect is may be something exceptionally demanding, such as a longer shaft... or do I have that backwards? I forget. Does the shaft extend out, or retract in when you pitch forwards?
Jeremy
-----Original Message----- From: Rod Bruckdorfer [mailto:seagypsy@att.net] Sent: Monday, January 13, 2003 11:52 AM To: bcc@yahoogroups.com Subject: Re: [bcc] Need more prop thrust in forward
Larry:
Do you have the full feathering prop - GSP engine? If you have hauled the boat, did you check the pitch while the boat was on the hard? We have the G engine which just has the variable pitch prop - large prop.
I do not believe you can expect much more than 4.5 knots from the 10 hp engine. Based on our experience, 4.5 knots is making good time in a chop. Perhaps Waxwings and Calypso can add more to the discussion.
Fair Winds,
Rod
I have attached an image of the prop shaft. You may want to talk to Bill Miller of Sabb America - 888-301-1706 - toll free.
Rod
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Jeremy, the shaft moves forward when you shift the pitch to forward.
Waxwing has the Sabb 10-G variable pitch(but not the full-feathering)
prop. It also has the larger two-blade, I think it’s 17 1/2 inches(?)
the smaller being 16 1/2(?).
I’ve only run the engine at its max rpm of 1800 a couple of times
because it tends to heat up in the warm waters of the Caribbean(and
sounds like a sewing machine on speed). It is raw water cooled. I
can only guess at the pitch setting but I do know it’s not at the
maximum because the engine starts lugging down and smoking at the
max. position.
Without actually having a tachometer, I’m estimating I run it about
1400 rpm with enough pitch to make 5 to 5 1/2 knots in flat water.
This is according to my knotmeter and GPS. Also, I usually have the
alternator cut out of the charge system when I’m trying to make a
cruising speed…it DOES make a difference because I can hear the rpm
drop when I kick in the alternator. I would guess it sucks an honest
2 hp when charging at 25 amps(on the guage).
Of course the proper way to set the engine up is to try different rpm
(using a tach.)with different pitch settings and then locking the
pitch control ‘stop’ lever, so you can always be running at ideal
pitch. But since I haven’t got a tach. and sometimes I charge while
running and sometimes not, I’ve never really locked the pitch screw
in any particular position. I just set the pitch arm, give it some
throttle and make adjustments later if necessary. (Very
unprofessional).
I will say that the Sabb 10 does not have the umph! to drive you into
a steep chop and stiff wind. But if you’ve got wind, you can sail and
that WILL drive you through. I have motor sailed short distances on a
couple of occasions when I just wanted to reach an anchorage before
dark and in that the Sabb is a big help.
As for judgeing if you are reaching max. pitch, I think you can
check the movement of the shaft. If I remember right, it should move
25MM (1 inch)from full astern to full ahead. If your shaft isn’t
moving a total of that distance, you probably need to adjust the
shaft length. But don’t panic. Depending on who put the shaft in the
shaft-coupling, their may be room to adjust the length of travel by
putting the shaft a little further into the coupling or pulling it
out slightly. You are probably talking less then 1/4 inch which their
should be not problem unless the shaft was bottomed out in the
coupling when installed. There is no problem with the amount
of ‘meat’ of the shaft in the coupling because the coupling is about
3 or 4 inches long.
If you disconnect the shaft coupling from the engine coupling you
should be able to push the shaft aft by hand until the blades are
feathered astern against their stop. Then pull the shaft forward as
far as it will go…it should be one inch. And at that point the two
halves of the couplings should be tight together and the pitch
control in the full forward position. If it isn’t, you aren’t getting
full pitch on the blaces because the shaft isn’t able to move forward
enough to induce the full twist.
I won’t get into how to correct that problem here, but it’s not that
hard. You just have to move the coupling a bit on the shaft (assuming
there is enough room to move it.
I can tell you that with full pitch the engine has a hard time coming
up to full rpm despite giving it full throttle. And if it doesn’t
come up to speed and remains ‘lugged’ down with the injector feeding
it more fuel then it can burn, it will smoke like crazy and heat up.
The Sabb really is just an auxillary for this displacement boat, but
with the proper settings it will run continuously for a long, long
time and never miss as beat. And if you have mechanical problems with
it you will have to fix it yourself because I think the last Sabb
mechanic in the US (there was only one I ever heard of)moved to
Canada and became a logger.
Stan on Waxwing.