RPM for cruising
I do not have my Universal manual here at home, but I believe that the M25 (21 hp) version should cruise at about 2400 to 2600 rpm. This would be quite similar to my 23 hp M25XP Universal.
At that speed we are at 6.0 to 6.2 kt, depending on how clean is the bottom.
At 2900 (as high as mine goes) I can do 6.8 or even 7.0 with a clean bottom.
When I got the boat it was doing about 5.8 at 1800 rpm, and was quite overpropped - fixed two-blade. It took me, as a newbie to inboards, a year to figure this out!
I replaced the fixed prop with a feathering two blade (Martec Autostream) in '95. So nowadays the pitch is whatever I adjust it to...
Loren in PDX
Olson 34
I do not have my Universal manual here at home, but I believe that the M25 (21 hp) version should cruise at about 2400 to 2600 rpm. This would be quite similar to my 23 hp M25XP Universal.
At that speed we are at 6.0 to 6.2 kt, depending on how clean is the bottom.
At 2900 (as high as mine goes) I can do 6.8 or even 7.0 with a clean bottom.
When I got the boat it was doing about 5.8 at 1800 rpm, and was quite overpropped - fixed two-blade. It took me, as a newbie to inboards, a year to figure this out!
I replaced the fixed prop with a feathering two blade (Martec Autostream) in '95. So nowadays the pitch is whatever I adjust it to...
Loren in PDX
Olson 34
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Richard Elliott
Member III
Engine RPM's
Chandelle, E34 #274 with M25XP does 6.3K at 2100 RPM's turning a three blade Max-Prop.
Chandelle, E34 #274 with M25XP does 6.3K at 2100 RPM's turning a three blade Max-Prop.
speed under power
I am pretty sure you can pick up some speed with a different pitch/dia prop-especiually in a seaway (waves).
The biggest thing is that you should have no fear at all of running at least 2500 rpm-possibly even 2700-2800 (this is about as high as I have seen any of the Universal diesels)-your manual should have something to say about this.
There will will be a big increase between 1800 and 2500, and IIRC-you should still not be burning much more than .75 gph-at 2500-2600 rpm.
As they say on the highway "Hammer Down" !!
Fair winds,
S
I am pretty sure you can pick up some speed with a different pitch/dia prop-especiually in a seaway (waves).
The biggest thing is that you should have no fear at all of running at least 2500 rpm-possibly even 2700-2800 (this is about as high as I have seen any of the Universal diesels)-your manual should have something to say about this.
There will will be a big increase between 1800 and 2500, and IIRC-you should still not be burning much more than .75 gph-at 2500-2600 rpm.
As they say on the highway "Hammer Down" !!
Fair winds,
S
R.p.m.
True Love, our 84 E35-3 #151 with a 24HP 3 cyl Universal and a 14" diameter and 10.5" pitch gives us around 6K at about 2200 RPM with a clean bottom. I believe we could have gone to 11" pitch with no problems. We tried 12" and it proved a bit too much. We selected 14" diameter as the largest size that gave proper clearance under hull (15% of diameter) to avoid hull interference vibration. The Universal manual specifies cruising RPM between 2100 and 2400. Maximum rated HP @ 2800. Using 21 HP. I think the 10.5 would be perfect, allowing for the 3 HP difference. If you can just reach 2800 at full throttle, your pitch should be OK. Ernie Schlesinger
True Love, our 84 E35-3 #151 with a 24HP 3 cyl Universal and a 14" diameter and 10.5" pitch gives us around 6K at about 2200 RPM with a clean bottom. I believe we could have gone to 11" pitch with no problems. We tried 12" and it proved a bit too much. We selected 14" diameter as the largest size that gave proper clearance under hull (15% of diameter) to avoid hull interference vibration. The Universal manual specifies cruising RPM between 2100 and 2400. Maximum rated HP @ 2800. Using 21 HP. I think the 10.5 would be perfect, allowing for the 3 HP difference. If you can just reach 2800 at full throttle, your pitch should be OK. Ernie Schlesinger
Chris Miller
Sustaining Member
Driver Seth...
I didn't know you drove trucks
"We'll see ya on the flip side. Until then, Driver- keep it between the ditches and the rubber on the bottom!"
Chris
FWIW our Tach gave out this summer and is on the list of replace-its. But our 38 does about 6 Knts while the motor hums real nice (around 60-70% throttle) with a 2 bladed folding max prop and cruiser paint.
Seth said:
I didn't know you drove trucks
"We'll see ya on the flip side. Until then, Driver- keep it between the ditches and the rubber on the bottom!"
Chris
FWIW our Tach gave out this summer and is on the list of replace-its. But our 38 does about 6 Knts while the motor hums real nice (around 60-70% throttle) with a 2 bladed folding max prop and cruiser paint.
"Prop"-er terminology
Hi Chris, One quibble if I may....
(and only because often these recurring prop discussions seem to get off course when quite different types are run together in the same thread.)
:eek:
If you have a "Max Prop" it is a feathering prop. Feathering props are also sold by Martec Engineering. I kind of suspect that you have a Max Prop featherer, not a folder.
Note that Martec sells folding and also feathering props, there are a lot of both installed in the last several decades.
Then there is the AutoProp, with the base of each blade rotating.
Y'all please identify which prop you are using, when posting...
Thank You,
Loren in PDX
(whose boat came with a fixed two-blade, and was changed to a feathering two-blade)
Hi Chris, One quibble if I may....
(and only because often these recurring prop discussions seem to get off course when quite different types are run together in the same thread.)
:eek:
If you have a "Max Prop" it is a feathering prop. Feathering props are also sold by Martec Engineering. I kind of suspect that you have a Max Prop featherer, not a folder.
Note that Martec sells folding and also feathering props, there are a lot of both installed in the last several decades.
Then there is the AutoProp, with the base of each blade rotating.
Y'all please identify which prop you are using, when posting...
Thank You,
Loren in PDX
(whose boat came with a fixed two-blade, and was changed to a feathering two-blade)
mark reed
Member III
more prop data
We have a 32hp Universal M40 and a two-bladed feathering Max-Prop, which I believe is 13" with 11" pitch (it was installed by the P.O.). We go about 7.1 kts at 2400rpm, which is 80% of the max RPM recommended by Universal. At that speed we burn about 3/4 gph. If we throttle down to 1800 we are still going 6 kts and only burning 1/2 gph, but I have been told that diesels should be run hard, as Seth suggested in an earlier post.
We have a 32hp Universal M40 and a two-bladed feathering Max-Prop, which I believe is 13" with 11" pitch (it was installed by the P.O.). We go about 7.1 kts at 2400rpm, which is 80% of the max RPM recommended by Universal. At that speed we burn about 3/4 gph. If we throttle down to 1800 we are still going 6 kts and only burning 1/2 gph, but I have been told that diesels should be run hard, as Seth suggested in an earlier post.
Chris Miller
Sustaining Member
Whoops...
Hey Loren, thanks for the clarification.
I know it's a Max Prop 2 blade (PO's have all the documentation for it) so I guess it's a feathering prop. We love it, other than the serious case of prop walk it gives us in reverse.
This is why I come here- always learning something new!
Chris
Hey Loren, thanks for the clarification.
I know it's a Max Prop 2 blade (PO's have all the documentation for it) so I guess it's a feathering prop. We love it, other than the serious case of prop walk it gives us in reverse.
This is why I come here- always learning something new!
Chris
Less prop walk with the max prop not more.
I have put a couple of maxprops on a few boats, and have found universaly that the prop walk is significantly better, IE there is less of it with the Max Prop than with standard fixed blade props.
Comparing it to folding props, the Maxprop actually works in reverse, and I have never seen a folder that really does much.
Guy
I have put a couple of maxprops on a few boats, and have found universaly that the prop walk is significantly better, IE there is less of it with the Max Prop than with standard fixed blade props.
Comparing it to folding props, the Maxprop actually works in reverse, and I have never seen a folder that really does much.
Guy
NateHanson
Sustaining Member
Yeah, I have to agree with Guy's MaxProp 'props'. The propwalk is less significant with MaxProp, and it has MUCH better reverse thrust than fixed or folding props.
Nate
Nate
Hammer down
Well, good buddy, I don't drive trucks, but in the 70's (like many of us-although few will still admit it) I had a CB in the car-still have my "10 code" booklet-And of course, while on the road doing my "day" job driving all over the Midwest, I keep an eye out for Smokey's, and try to make truckers believe that not all "4 wheelers" are driven by idiots!
Breaker, Breaker!
Well, good buddy, I don't drive trucks, but in the 70's (like many of us-although few will still admit it) I had a CB in the car-still have my "10 code" booklet-And of course, while on the road doing my "day" job driving all over the Midwest, I keep an eye out for Smokey's, and try to make truckers believe that not all "4 wheelers" are driven by idiots!
Breaker, Breaker!
I second (or third) that motion
My experiences allign with those of Guy and Nate...
The feathering Martec is more powerful in reverse and almost all of the previous prop walk in reverse went away. This was in comparison to the stock two blade fixed prop.
Funny as it sounds, the benefits of reverse power were almost worth more than the lowered drag under sail.
A diesel mechanic in our YC also advises to keep the revs up in the cruising range specified by the manufacturer, which for our late 80's Universal is 2400 to 2600 rpm. Actually, our engine runs just as smooth maxed out at about 2900 rpm indicated, and 6.8 kts. I save that for times when I am really in a hurry, however.
"Hammer Down, good buddy"
"Breaker Breaker, any takers? CB Savage Calling...."
"This here's the Duck!"
Ya don't hear that on the radio (around here) any more...
Loren in PDX
Olson 34 #8
My experiences allign with those of Guy and Nate...
The feathering Martec is more powerful in reverse and almost all of the previous prop walk in reverse went away. This was in comparison to the stock two blade fixed prop.
Funny as it sounds, the benefits of reverse power were almost worth more than the lowered drag under sail.
A diesel mechanic in our YC also advises to keep the revs up in the cruising range specified by the manufacturer, which for our late 80's Universal is 2400 to 2600 rpm. Actually, our engine runs just as smooth maxed out at about 2900 rpm indicated, and 6.8 kts. I save that for times when I am really in a hurry, however.
"Hammer Down, good buddy"
"Breaker Breaker, any takers? CB Savage Calling...."
"This here's the Duck!"
Ya don't hear that on the radio (around here) any more...Loren in PDX
Olson 34 #8
Richard Elliott
Member III
rpm's and boat speed
I had a two blade Max Prop on an Islander 28 which dramatically improved reverse but still had significant prop walk. The three blade Max Prop on our E34 has much less prop walk. Interestingly, I met the new Islander owner and he has changed to a three blade Max Prop. A word of warning for do-it-yourselfers, the three blade is much more difficult to install, requiring a second pair of hands.
I had a two blade Max Prop on an Islander 28 which dramatically improved reverse but still had significant prop walk. The three blade Max Prop on our E34 has much less prop walk. Interestingly, I met the new Islander owner and he has changed to a three blade Max Prop. A word of warning for do-it-yourselfers, the three blade is much more difficult to install, requiring a second pair of hands.
Chris Miller
Sustaining Member
Slap me...
So in looking through the boat maintenance photos and then at the Max Prop website... Umm, that would be a folding prop. My bad. I guess somebody was shopping for one and never bought it, just stuck the info in the "we own these things" book- and I didn't know exactly what they looked like. Seems a little pricey, but if they work as well as it sounds like-it's probably worth it. That's a lot of sail money, though...
Sorry about the mix-up,
Chris
So in looking through the boat maintenance photos and then at the Max Prop website... Umm, that would be a folding prop. My bad. I guess somebody was shopping for one and never bought it, just stuck the info in the "we own these things" book- and I didn't know exactly what they looked like. Seems a little pricey, but if they work as well as it sounds like-it's probably worth it. That's a lot of sail money, though...
Sorry about the mix-up,
Chris
paul culver
Member III
Boat speed
Several responders have touched on the importance of a clean hull. I recently purchased an E29 and when I took possession and finally got it out on the water after two months it was significantly slower than my sea trial --even at full throttle. A diver cleaned the hull and prop and the speed came right back up. I suspect the prop was the major culprit since it had some sort of worm growth attached to it.
Good luck!
Several responders have touched on the importance of a clean hull. I recently purchased an E29 and when I took possession and finally got it out on the water after two months it was significantly slower than my sea trial --even at full throttle. A diver cleaned the hull and prop and the speed came right back up. I suspect the prop was the major culprit since it had some sort of worm growth attached to it.
Good luck!
Yes!! If your prop does not have a smooth surface it will not get a clean cut thru the water. Like a wing on an aeroplane. A rough surface on a wing will not produce lift because of disturbed airflow. The prop won't cut and push the water properly if the water is disturbed. This is not to negate the fact that a dirty hull will slow down a boat, But if you have a clean hull and a dirty prop your boat will probly go slower than if you had a dirty hull and a clean propeller.
Kind of like having the air pressure in your tires too low. You have to give it more gas to keep the same speed that you would have at the proper pressure.
Just my $.02 worth
Davis
E29
#224
Holy Guacamole
Davis Modlin Atomic 4
Kind of like having the air pressure in your tires too low. You have to give it more gas to keep the same speed that you would have at the proper pressure.
Just my $.02 worth
Davis
E29
#224
Holy Guacamole
Davis Modlin Atomic 4