Specs for 2005 340 Props - Inboards

Hampton

Air Defense Dept
TECHNICAL Contributor
Nov 26, 2006
7,628
Panama City, Fl
Boat Info
2008 44 Sedan Bridge
Engines
Cummins QSC-500's
Straight Drives
Does anyone know the specs or can anyone point me in the right direction, or, would the Wheel Shop know what my boat is supposed to have? (South Port, Fl)

I'll probably get them tuned next week. I understand that they are different (P vs S) due to one transmission running in reverse and having different gearing.

I was in the engine room at 1250 RPM (both sides) cruise the other day, and the port shaft really appeared to be spinning more slowly. That one uses less fuel (13 vs 15 gph). I shouldn't be able to see the difference in rotation rate though, should I?
 
John,

There's a place somewhere on searay.com that will have the specs for the original props.

No, the props should be the same diameter and pitch, just port and stbd for the reversed rotation of the stbd side transmission, so the RPM should absolutely be the same. Do you see a difference in RPM on the tachs when cruising?

I suppose that a previous owner could have dinged a prop and it either was repaired to a different pitch than original, or it was replaced with one that had the wrong pitch.

Both props should even be from the same manufacturer, as props with the same quoted diameter and pitch can have a different surface area, which will effect RPM.
 
John,

There was a discussion regarding this topic on the old forum before it moved. I was informed that due to one transmission running in reverse (confirmed), the gearing was different, so the props were a different diameter. The previous owner did ding a prop, and I had them tuned before cruising home - The port one has always used less gas, so I suspect the prop shop smoothed it out, but didn't re-spec the props.

I have seen the SR specs on these props, and the dia's were slightly different, but I don't remember the numbers right now. The pitch's weren't listed as I recall.
 
Thanks!!!!!!!!!

2005
340SDA
TVD-8.1 S (T-370 PHP) MCM V-DR. INBOARDS
N/A (Drive type)
2.00:1
18"X 21"X 4.85" "Z" RH
1765069
4600
18"X 21.5"X 4.85" "Z" LH
1752175

One prop is 1/2" larger - Is RH the stbd prop, or RH spin direction, or both?

My WOT RPM's indicate: P - 4850 with throttle back 1-2 knob widths; S - 4650 full up.
 
John,

I was just going to post the address for the prop charts but Dave S beat me to it.

Yes, I also checked it out, and am really surprised that the one prop has more pitch.

The first figure of 18" is the diameter, and the second is the pitch, so the left hand rotation prop has 1/2" more pitch than the other.

As for which is which, here's what I know to be fact...

The port side motor has a 'standard' rotation on your boat just like my old 340EC, that is, it is the same as a passenger car, and rotates clockwise from the front of the motor. That would be counter-clockwise looking from the rear, so I suppose that the prop for that side would be considered LH, left hand rotating. That would make sense as that's the one you have a higher RPM on, and more pitch would fix that.

What I'm confused about is the the difference in RPM in the two sides. Generally, 1" of pitch equals 200 RPM, and you have that much without using full throttle on the higher RPM side.

It probably goes back to the repair on the prop. You didn't exactly say that it was the port side that got dinged, but that would sure fit the puzzle.

I might look for a different shop, or if you think they're OK, talk to them. My local prop shop uses some high-accuracy computer program with a dial indicator of sorts that runs up the prop blades and registers it on the screen. A prop can be 'fixed' but no longer have the exact profile, or curve in the blade, that it did originally.

I don't know if I've helped or confused you more, but it sure seems like the repaired prop is the direction to look.
 
John,

Just pull the wheels and take them to Buck at Marine Wheels.......he's now at Miller Marine in Southport........tell him what you currently are yielding in rpm's and what you want. They do have a computer digitizing device and there is nobody any better than Buck at doing this.

My advice is don't go out there telling him what to do, how many inches to take out or add in., etc. Just tell him what you have and what you need and write the check......leave the rest to him.
 
For fwebster....is it your experience that SR props new boats correctly & the props are not in need of tuning? I've wondered if sending my props to Buck would do any good? I do not have any problem & WOT rpms, S&P, are spec & the same. What am I looking for?....don't know, just curious if having a master do his magic would improve anything.
 
Frank et al,

First of all, you all help a million.

The props were tuned in Miami by - I don't know who. I plan on going to Buck and doing just as you say. I will be curious to learn what they find.
 
You're right. I went back and looked again. It must have been a lighting issue or the fact that one cotter key sticks out while the other is completely rapped around causing a visual illusion.

I dropped my props off today along with the copies of your prop data chart - thanks.

The props rotate outboard (tops to sides). Some tow boats rotate the other way to create lift for shallow water operations.

You can differentiate most (non-tow) boat props by reaching down to pick them up with your right hand. The stbd prop is easys to pick up. The port is not because the next blade is in the way of your thumb. This is with the thumb near the hub.

My port prop was supposed to have 1/2" more pitch to make up for the differential gearing in the reverse-running transmission. I'm guessing that when I had them tuned in Miami by the random Cuban Brothers (made-up name), they matched the props. Therefore, the port is spinning too freely, and allowing 4850 RPM instead of the book answer of 4600.

I hope they are close after this. At cruise the stbd used 2 gph more than the port. Add on the gen to the stbd fuel tank, and there was a significant mis-match.
 

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