Advice on Propeller Pitch Adjustment to Match Cruise HP at 3,000 RPM

[HighFly_27]

Hello All,

1st, I've researched the internet for about two weeks but still need some guidance/ advice.

I just bought a (as new/ never installed) Hydralign Propeller that was bought as a spare for another sailboat. The Hydra. Prop. is a close match up to the 3 blade, 13 3/4 in. diameter, fixed pitch on my 1970 Islander 37 MS.

Problem/ Question:

I will be (most likely) need to make a small pitch adjustment to match this propeller to my I-37, Perkins, 50 HP for a Motor Sailor (MS). My boat is about 5,000 pounds heavier than the North 'Sea 27 with a 27 HP (?) diesel installed. I assume, this propeller was set up (new) to match up to the North ' Sea 27 and will require an added pitch adjustment for my I-37.

My Researched Information:

My Perkins is Rated at 50 HP but known to be lower in output, closer to 42 to 45 HP in actual HP output.

I have been advised by a Propeller Vendor for Gori, to figure my Perkins (4-108 M) @ 40 HP @ 3,000 RPM. I have a 1.5 to : 1 radio gear box.

I have Zero paperwork for the Hydralign Propeller. I have requested it but nothing yet.

*** My Pitch/ Adjustment Question:

Bottom Line Results -- Do I Adjust the Propellers Pitch to... just reach the Governed RPM of -- 3,600 RPM on the Perkins 4-108 M Diesel Engine ?!?

I understand that I will operate this engine around 3,000 RPM about 70 % of the time or slightly less in RPM on a day to day basis. I'm a retired diesel mechanic and knowledgeable about proper engine operation. To Not operate in a -- lug (over prop'd.) or excessive idling, allowing the engine to operate cold & washing cylinder walls down, etc. .

Thanks in Advance,

Avery

[Nineteen]

Hi Avery

I guess you havent spoken to George yet???

The adjustment is discussed in the link below.

http://www.hydralignprop.com/operation.html

I set mine to just get max rpm with a clean prop and bottom. If you are not sure what your prop should be set start with your pinion at the 0 index and try it. If you achieve full rpm before hull speed is reached just turn the pinion in the direction of rotation incrementally until you get max rpm where you want it. The reverse is true. If you end up with too much pitch and are unable to get the desired max rpm retard the pinion in the direction opposite.

If you still cant achieve the rpm you want at the #8 index you will need a different diameter.

Cheers
Tom

[Nineteen]

Hi Avery

This video will show you the adjustment process. You should adjust to just get max governed rpm.

Cheers
Tom


Hydralign Aperture A assembly - Right Hand: http://youtu.be/7Os1GHDNjZY

[Nineteen]

Hi Avery

The link below shows George axjusting a Senior mosel.
You should set the prop to just get the 3600 rpm when everything is clean.

I would start with the pinion set to the #0 index and then rotate the pinion in the direction of rotation to increase the pitch or against the direction of rotation to reduce pitch.

You can only go to + or - #8 either way otherwise you would need to change the diameter.

This is also described under 'Operation' on the website.

Cheers
Tom




Hydralign Aperture A assembly - Right Hand: http://youtu.be/7Os1GHDNjZY

[Nineteen]

Sorry about the multiple posts - I had phone trouble...
Cheers
Tom

[westwinds]

Better check with the propeller manufacturer because of the difference in size between the two boats. If the propeller is too small, even if you manage to adjust the pitch to get a reasonable maximum RPM, you will likely have a cavitation problem and that can destroy the propeller by eroding the propeller material.

[Cheechako]

Don't go overboard on pitching for max rpm. My 44 ft cutter had the 4-108 in it and I rarely ran over 2600-2800 rpm. Real sweet engine at 2450-2600 rpm. Should be plenty of HP for your 37 footer. I had a 16" Max Prop, cant remember where the pitch ended up though.
Had a 39 ft waterline and reached hull speed of about 8.5 knots at 2800.

[HighFly_27]

19 & All,

I sent two (a week apart) emails to JBC Yacht Engineering and No reply. I did not address it to -- George, perhaps I should have.

I sent the same information request to North-by-West. I received a email from NbW yesterday. They told me that they no longer handled Hydralign and I should contact JBC.

My Requested the following:

1st, I described my Hydralign Prop. by the stamped in -- Model/ S/N.

Requested -- Owners Manual, Parts Manual and Pricing List & any other documentation that a owner would have received with a new propeller.

I requested (to buy) (2) tubes of grease to complete (1) service of the hub now and a 2nd a year later & (1) Zink Anode.

I sent my request to the one & only -- JBC Contact Email Address as listed on their web site.

** I don't have a clue about why I have not received a follow-on email from JBC ?!?

*** I have seen the Hydralign clip on You Tube on setting up of the Aperture Prop., looks simple enough.

**** I get it (now) about dialing in the pitch to .. just obtain max. engine RPM at Governed RPM. I toyed with the idea that I'd set the prop. pitch to obtain 3,400 or 3,500 RPM... In-Stead of 3,600 Governed RPM. It may be to my advantage for a slightly over prop'd. setting to conserve fuel at my intended Cruise RPM of -- 2,700 to 3,000 RPM.

However, I did not want to place the engine in a constant deep lug load situation. If I was testing for a deep lug in a truck, It's fairly easy to verify. If you can accelerate out of lug, you are not damaging the engines lower end (rod bearings). A deep lug pounds the hell out of the connecting rods and rod bearings. My Example >> Cummins Engine Governed Operating RPM Data for -- 855 CI Engine is >> Max. No Load = 2,300, Gov. RPM with Load = 2,100, Lowest Shift RPM = 1,650 RPM. Lower than 1,600 is the beginning of a DEEP LUG and will cause shortened engine life or component (rods) failure(s). I assume that I can apply these -- load/ torque/ hp/ rpm data values from one engine to another for a comparison study.

*** I (now) understand, that a Prop. may be over pitched to obtain these results but (may) enter into capitation (early on) to do so. I can't mount a bigger diameter prop. on my I-37. A 14 in. diameter prop. is about the max. size D. with the 15 % dia. keel clearance requirement.

Thanks A Lot,

Avery

[Nineteen]

Hi Avery,

I just tried George on the phone. He has been busy but said he will check his emails and get back to you.

Here is the JBC/Hydralign contact info as a backup( I'm sure you would already have this).

I know with your background you have handle on what you are doing with the prop and I hope you get as good a run with your Type A as I have with my Senior.

Cheers
Tom

Phone:
Within Australia - (02) 9957 5123
International - (61 2) 9957 5123
Fax:
Within Australia - (02) 9925 0082
International - (61 2) 9925 0082
Email:
office@hydralignprop.com
Address and Mailing:
JBC Yacht Engineering
4/1 Bradly Avenue, Milsons Point
NSW, Sydney, Australia, 2061