HyTorq props for 410DA

[markrinker]

HyTorq vs ACME props for 410DA

Pulled props and had them spec'd on a Hale MRI at Propulsion, Inc of Hudson, WI. (715)386-2547 www.propfix.com

Everything checked out fine, with the exception of the pitch on each was closer to 26p, than 25 as the props are stamped... :huh:

LH = 22"x25p - Actual pitch average of all blades is 25.791
RH = 22"x25p - Actual pitch average of all blades is 25.639


This might explain the slight run slow from 2800rpm WOT spec.


I am looking for a set of "spot on" 22"x25p props, if anyone knows of a pair for sale.


Another question - I have 3" of tunnel clearance around my OEM props. Is there any efficiency gained by running 24" diameter? Would you back off on pitch or run same?

 

[fwebster]

The general rule of thumb is that the clearance between the hull and the blade tip should be 1/6th to 1/7th of the prop diameter. The 22's were the maximum that should be fitted on the 410 which is why Sea Ray chose them. The efficiency question doesn't matter because there would be so much cavitation that the props wouldn't hold anyway.

On a fully loaded boat your engines should turn up 2800rpm @ WOT. You don't tell us what rpms you are achieving, but as a general rule of thumb, 1" of pitch is worth about 300 rpm. My guess is that you are a lot closer to rated rpm's than 300 rpm. It may be that all you need is to have a little of the cup removed from the props. While prop scanning equipment will accurately measure a prop, the guy doing the work still has to use a hammer and gauge blocks to add or remove pitch. Doing the right thing to hit a desired rpm is about as much art as it is science, so us ignorant boat owners should never get in the business of telling the prop pro what to do.....just tell them you need 50 or whatever more/less rpms and let the artist do what he needs to to get the desired result. Handling it that way also means the prop guy will probably tweek your wheels as needed in case he is off the first time.

 

[markrinker]

Hey Frank -

Thanks for the diameter information. Makes sense now.

I can make 2800 RPM WOT under ideal circumstances - i.e. fresh fuel filters, light boat, cool day, smooth seas. I would say that my average observed WOT would be 2700, or about 100rpms slow. If 'fully loaded' means full of fuel, full of freshwater, four people and gear, then my RPMs at WOT (even with fresh filters) would be 2650.

Sounds like they need to be hammered back to a true 25p set, as Sea Ray intended them to be! (But I understand your advice not to get into advising the artist - just tell them how many RPMs you want!)

Question: What is the effect of three blade configurations? Five blade? I am sure that Sea Ray uses four blade for a good reason (all around mixed use), but trying to understand the physics behind that selection...if you went to three you'd need more pitch, and five would need less, correct?

Last question - what would you expect the WOT RPMs to be with a set of 22 x 28 3 Blade props? A three blade configuration would favor a boat that is used on plane over long distances, where a five blade would favor a boat that spends most of its time at hull speed, correct?

 

[fwebster]

I am not a prop specialist, but I have spent a lot of time with boats over the years, so here is my take on your questions: You never see diesels, other than sailboats with very low power, with 3 blade props. I believe that is because the torque diesels put out is so great that it would take a lot of pitch on 3 blades to deliver the right rpms. The more pitch you have the more race boat-like the performance is....i.e. hard to plane with losts of slippage and props breaking loose and losing their bite. At this level of boating, the more blades on the prop, the less pitch is required/blade and the more efficient the props because the higher the pitch, the more the slippage and the lower the efficiency. The other facet is smoothness........the more blades on the prop means less pitch per blade that means less slippage and that translates into a smoother ride. We are seeing the high performance sportfishermen class of boats with 5 and 6 blades now. These are 80-90,000 boats with 4-5000hp that run 40 mph, so I don't think the assumption that more blades = slower boats works. I might also add that the cost of a 36" 5 blade prop is something like $35,000 so I think you can draw the conclusion that more blades = more engineering and higher prop costs.

All of this is theoretical since it appears that you have the right diameter and are within about an inch of having the right pitch on your present set up.

 

[markrinker]

ACME calls for a 22"x25p four blade. They modify the cup port to starboard, based on the ZF specs which I do not have close at hand today. I have access to a set of 22"x23p three blade that would be an interesting test. My theory is that WOT would be well beyond 2800rpm, but the props could be reworked from that finding to bring the RPMs to spec. Either way, I'll keep my original HyTorqs unmolested as ready spares, or for when the boat is sold.

 

[ttmott]

They modify the cup port to starboard, based on the ZF specs which I do not have close at hand today.QUOTE]

The ZF's have a slightly different gear ratio in reverse than forward and as the port trans runs in reverse with the starboard in forward there will be a slight difference in shaft speeds at same engine RPM's. However, it is such a small difference in ratio I'm suprised that the props are tailored to such.

 

[fwebster]

They modify the cup port to starboard, based on the ZF specs which I do not have close at hand today.QUOTE]

The ZF's have a slightly different gear ratio in reverse than forward and as the port trans runs in reverse with the starboard in forward there will be a slight difference in shaft speeds at same engine RPM's. However, it is such a small difference in ratio I'm suprised that the props are tailored to such.

I do not think that is correct for the transmission used behind the diesel engine option. The Cat engines should have had Hurth HSW-800-IV (later called the ZF 80-IV) and they have the same ratio in either direction. Sea Ray did prop the stbd slightly different than the port, by 1/2" of pitch, on boats with the Hurth 630-IV/ZF 63-IV which does have a slightly different ratio in forward than in reverse. Those were usually 8.1L Mercruiser engine powered boats where the rpms could be high enough for the ratio difference to cause harmonic vibrations.

However, if the marine gear in the 410DA is the ZF-630 series, then Tom is right...................

 

[HUMPH]

My specs are for 22X23 and I had some pitch taken out. 22X25 is too much IMO.

 

[ttmott]

I do not think that is correct for the transmission used behind the diesel engine option. The Cat engines should have had Hurth HSW-800-IV (later called the ZF 80-IV) and they have the same ratio in either direction. Sea Ray did prop the stbd slightly different than the port, by 1/2" of pitch, on boats with the Hurth 630-IV/ZF 63-IV which does have a slightly different ratio in forward than in reverse. Those were usually 8.1L Mercruiser engine powered boats where the rpms could be high enough for the ratio difference to cause harmonic vibrations.

However, if the marine gear in the 410DA is the ZF-630 series, then Tom is right...................

I was more looking at the Hurth HSW 800IV, ZF 80IV, and ZF 85IV which are all the same with the ZF 85IV being an improved more robust design. In the ZF literature for the various ratings there are three ratios available for these transmissions of which each ratio has a listing for "A Position" and "B Position" (engine direction of rotation and reverse; reverse runs against the transmission's countershaft). Listed as A position/B position the ratios are as follows: 1.644/1.638, 2.008/1.996, and 2.493/2.468. Assuming the port transmission in forward boat motion is "B position" (running against the transmission's countershaft) and starboard transmission in forward boat motion is "A position" (not running against the transmission's countershaft) then it stands to reason to make all equal more pitch is required in the starboard prop. Hence my assumption for the reason they put a steeper prop on the starboard side.... So, should one desire to change the props or desire to change the pitch on the props the ratio differences in the transmissions should be a factor.

 

[fwebster]

Here are the spec sheets for the ZF 80 and ZF 85 marine gears:

http://www.tadiesels.com/transmissions/ZF_Hurth/brochures/ZF_80_A.pdf

http://www.tadiesels.com/transmissions/ZF_Hurth/brochures/ZF_85_A.pdf


I don't have any Hurth info since ZF bought them some time ago. You are correct, they are all the same transmission but the spec sheets show the A & B ratios to be the same in both directions.


I can't fault your logic in the different pitch props, but I have never seen it on a diesel powered boat, only on 8.1 Merc powered ones.

 

[markrinker]

My specs are for 22X23 and I had some pitch taken out. 22X25 is too much IMO.

My CATs are set up at 385hp so that might be the reason for the 22x25p prop selection. It is* slightly overpropped, but can make 2800 under 'idea' conditions, but tends to run slightly slower than that when tested under a variety of conditions...the most notable is age of main Racor filters, and that is a fuel flow issue, not a loading issue.


Question: What are your max RPMs at 350hp rating with 22x23p wheels? Do you know what transmissions and gear ratio you have?

 

[ttmott]

Here are the spec sheets for the ZF 80 and ZF 85 marine gears:

http://www.tadiesels.com/transmissions/ZF_Hurth/brochures/ZF_80_A.pdf

http://www.tadiesels.com/transmissions/ZF_Hurth/brochures/ZF_85_A.pdf


I don't have any Hurth info since ZF bought them some time ago. You are correct, they are all the same transmission but the spec sheets show the A & B ratios to be the same in both directions.


I can't fault your logic in the different pitch props, but I have never seen it on a diesel powered boat, only on 8.1 Merc powered ones.

For the literature you are showing Frank you are correct but those are Straight Drive marine gears. The Sundancer's V drives (the IV designation on the transmission model numbers) have different ratios A and B positions.
http://www.zf.com/corporate/en/prod.../boats/matching_tool/matching_tool_large.html

 

[fwebster]

Ok.....I give up. The source I was using just showed the inboard transmission and not v-drives.

But it is a moot point on boats like the one in question. No matter what the final ratio in A or B settings is, the set op on 400/410/450......and any of the diesel powered boats is that the engines turn so slow (26-2800 rpm) and have so much torque that Sea Ray used the 2.5:1 ratio gearing. That means the prop shaft is turning slow enough that the difference in ratios makes no real difference in performance and the boats are spec'd with the same prop on both sides. The gas engines, however, are a different story. They turn something like 4200 rpm and have 2.0:1 or lower gearing and that makes the prop turn about twice as fast as on a diesel boat. and on hulls like the 340DA, they put .5" more pitch on one side than on the other.

Thanks for keeping me straight...............

 

[Southpaw II]

Ok.....I give up. The source I was using just showed the inboard transmission and not v-drives.

But it is a moot point on boats like the one in question. No matter what the final ratio in A or B settings is, the set op on 400/410/450......and any of the diesel powered boats is that the engines turn so slow (26-2800 rpm) and have so much torque that Sea Ray used the 2.5:1 ratio gearing. That means the prop shaft is turning slow enough that the difference in ratios makes no real difference in performance and the boats are spec'd with the same prop on both sides. The gas engines, however, are a different story. They turn something like 4200 rpm and have 2.0:1 or lower gearing and that makes the prop turn about twice as fast as on a diesel boat. and on hulls like the 340DA, they put .5" more pitch on one side than on the other.

Thanks for keeping me straight...............

Frank.....check those numbers. :grin:

Don

 

[markrinker]

Every day is school day at Club Sea Ray. (I'm a poet, and don't know it.)

So I found a set of new in box old stock ACME 22"x23p three blades that were cut for a company that did testing for Yanmar on Cruisers hulls. Talked to the engineer that tested three and four blades configs on 40' Cruisers hulls, and he was pro three blade for my described boat config and use.

At the worst case, they make an inexpensive set of backup props to get me home from the inside passage to Seattle for repairs if I whack a rock or a submerged log someday. Best case, I have them pitched up to bring down the rpms to 2800, and save some fuel with my typical boat config and use of 'light and on plane over long distances'.

Can't wait to get in the water with this new set bolted in place and see what happens under acceleration, at WOT, etc.

 

[carterchapman]

Frank,

No good deed goes unpunished.


Mark,

I'll be interested to see the performance difference with 3 bladed props. I know they are a different boat/engine combo, but the '03 1/2 340s with 8.1s had 3 bladed props. Searay switched to 4 bladed props in '04 (same engines and hull) and there was quite a performance improvement.

You've probably reviewed this thread, but here's what the late Dominic (OSD9) did to One Sweet Day's props:

http://clubsearay.com/showthread.php/3566-410DA-performance?highlight=aetna

 

[mistercomputerman]

Dom was the man...I miss his shiny head around here.

 

[markrinker]

Frank,

No good deed goes unpunished.


Mark,

I'll be interested to see the performance difference with 3 bladed props. I know they are a different boat/engine combo, but the '03 1/2 340s with 8.1s had 3 bladed props. Searay switched to 4 bladed props in '04 (same engines and hull) and there was quite a performance improvement.

You've probably reviewed this thread, but here's what the late Dominic (OSD9) did to One Sweet Day's props:

http://clubsearay.com/showthread.php/3566-410DA-performance?highlight=aetna

I really fell in love with the technology and methods behind the ACMEs, but couldn't possibly afford a replacement set in 22x25 right now...this set gives me a spare and low(er) cost entry to experimenting a bit. I didn't pay their ask - and got free shipping to boot....

When searching the internet, I came across this Sea Ray 420 of a different era and similar CAT power, with the same 22x23 wheels....made me feel more confident in my choice.

http://providence.craigslist.org/boa/3674209050.html


We shall see! Too bad they are below the waterline because I think they look COOL :thumbsup:

 

[carterchapman]

Dom was the man...I miss his shiny head around here.

Me too Rick. I've searched out and archived every one of his threads....

 

[HUMPH]

Frank,

No good deed goes unpunished.


Mark,

I'll be interested to see the performance difference with 3 bladed props. I know they are a different boat/engine combo, but the '03 1/2 340s with 8.1s had 3 bladed props. Searay switched to 4 bladed props in '04 (same engines and hull) and there was quite a performance improvement.

You've probably reviewed this thread, but here's what the late Dominic (OSD9) did to One Sweet Day's props:

http://clubsearay.com/showthread.php/3566-410DA-performance?highlight=aetna

Yep, great thread. Dom helped me with some of his data when I was having my propscan done. I still need to do his tach upgrade still! Can't wait to honor the man I never met this July!