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35' Command Bridge prop size

Posted: Sat Aug 24, 2013 12:53 pm
by Drebello
I have 35' Command bridge with a 370 Yanmar ZF801V 2.49 ratio transmission. I'm looking for some advise on the best pitch to start with. I just purchased this vessel and its way over propped now. im only hitting 3100 RPM's with low water and low fuel aboard, no gear.

I understand how to re pitch the boat but since im way off especially when I load her up im looking for a good starting off point. I hear re pitching to much is a bad thing. What can I expect from fuel economy at trawler speed with this motor package?. thank you all in advance for your advice!

Re: 35' Command Bridge prop size

Posted: Sun Mar 25, 2018 7:16 pm
by scottymags
I’d like informarion on this as well. We have the same setup and would like to maximize cruise speed and fuel efficiency and one option is to get a new prop. What should we be aiming for?

Re: 35' Command Bridge prop size

Posted: Mon Mar 26, 2018 9:27 am
by GOING COASTAL
I assume you have the same boat with a 370 Yanmar and a zf gear, the max rpm for the motor wide open is 3,300 rpm so load the boat as you would most often use it and run it wide open in normal seas and see what the current max rpm is. If its not with in specs have the prop removed and find a prop repair place in your area and they should be able to adjust it to meet the specs. I need to do the same thing with my 35cb one day soon

Re: 35' Command Bridge prop size

Posted: Mon Mar 26, 2018 2:39 pm
by dmorlo52
I was over propped as well on 35TE with 6LY2A-STP 440hp and went through multiple iterations to get it right. Went from 25x23 all the way down to 24x19. Original prop was 26x24 and second owner had it trimmed and pitched to 25x23 and analog tach said it was getting 3300 WOT. I put in flow-scan and new digital tach and true rpm was only 2800 WOT. (photo tach verified 2800 WOT) Original tach was reading 450-500 rpm high.

Called John at H&H propeller in MA and told me they put 24x19 on the 35TE with my engine and they made them for Albin for years. Ordered this one and put it on in the spring and still only got 3100 WOT. So prop was taken off fall 2016 and John re-pithed to 24x17 (for no charge) and now getting 3500 WOT (+/-) a little.

First - photo tach your motor to get true rpm if low call H&H as they are familiar with the Albins and have computer program to determine correct prop.

I do have the 25x23 LH in great condition if anyone has a need for prop this big.

David
Winedown 35TE

Re: 35' Command Bridge prop size

Posted: Mon Mar 26, 2018 4:31 pm
by thomaslong
So what would it mean if the laser tach read 500 rpms low on both cruise and WOT in an Albin CB 32+2 powered by the Yanmar 6 LY2A 350 hp? Yet the boat hit speeds of 15 knots at cruising and 18 WOT. The analog Yanmar tach was reading 3100 and 3500 at those respective speeds, the laser read about 2600 and 2975. When powered up, the boat jumped right up on step in six seconds with no smoke or hesitation and ran great. Fuel and water were about half full, but we were carrying six adults.

Re: 35' Command Bridge prop size

Posted: Mon Mar 26, 2018 7:17 pm
by dmorlo52
I did make a mistake in my last post as my WOT is now 3300 which is what it should be +/- depending on load. If your photo tach is reading lower than the Yanmar tach then I guess you are over propped. The photo tach is your accurate rpm. You should also get about 3600 rpm WOT in neutral with no load? The way I understand it if you drop the diameter by 1" you should pick up about 200 more rpm. By changing pitch from 19 to 17 I picked up about 200as well. Before using the 24x17 I did not have any black smoke or other performance issues just lack of correct rpm. My engine now performs very close to the Yanmar rpm and fuel consumption table in the manual. I lost about 3 miles per hour on high end at WOT but the hole shot is awesome. I cruise at 14-16 knots and can hit 19WOT depending on fuel load, etc. At 15 knots I get about 1.3 miles/gal.

David

If Rob S. can chime in here he can verify if I am right.

Re: 35' Command Bridge prop size

Posted: Tue Mar 27, 2018 3:06 pm
by jmfernan
I recently purchased a 32+2 with Yanmar 370 and 2:1 gear. Boat was repowered in 2006 from a Cummins. As purchased we had a 4 blade DQ wheel 23x18 and reached 3300 WOT. Tach is Maretron interfaced to the 6LY with EMS 100 (which works great), and was verified with laser tach. We had the boat weighed on a truck scale when it was shipped and it was 15,000 lbs on the nose, tanks empty, including hard top and bimini.

Research and consultation with Tony Athens at Seaboard Marine lead me to conclude that this motor should be propped to 3425-3525 fully loaded. See attached guide. We pulled the prop and had it scanned, ultimately deciding to go with a new 4 blade Acme 22x19 with med cup. With 200 gal fuel and two heavy guys we reached 3450+ WOT and 21+ knots. If you have a 2.5:1 gear or 6LY2 440 you could go with a bigger prop, up to 24 inches I think.

Since then I updated the exhaust elbow with a stainless unit with coolant flow switch to alarm any loss of coolant water. I added a ‘Turbocator’ boost and exhaust temp gauge (EGT). Pyro is located before the turbo.
After spending a few months in the water (bottom cleaned but not pristine) here are our typical values:
• At 2750 rpm EGT is 1150 deg F and boost is 17 lbs. 15-16 knots.
• At 2850 EGT is 1150 deg F and boost is 19 lbs. 16-17 knots.
• At 3450 EGT is 1340 deg F and boost is 30+ lbs. 21+ knots.
Remember, these EGT values are pre-turbo. Tony recommended cruising below 2,900 and said the numbers look good. Hope this helps and let me know if you have questions.
Joe
1999 32+2
Santa Barbara CA