Adagio has a Universal M35 and a two blade MaxProp. Shortly after buying her we hauled out for some bottom work which included replacing the cutlass bearing. The yard also pulled the prop to check the shaft and the inside of the prop. I was asked then if I knew the pitch the prop was set at. At the time I was not familiar with the MaxProp at all. I was told they would said it according PYI’s recommendation based on my transmission.
Ever since the boat has been in the water I have never been able to cruise over 1800 RPM without the engine starting to get hot (190+). At 1800 RPM I run about 6.5 knots with no heating issues (stays between 160-175). By adding 200 RPM it will get to 190 and will climb higher if I keep pushing. In addition to that, when under load at these speeds a white steam starts coming from the exhaust. My solution over the last year has been to cruise at 1800.
After some research it seems the cruise RPM should be around 2200 RPM to keep the engine healthy. That got me to work trying to figure out the issue. My first thought is I am overpropped but before hauling to adjust the pitch I spent the last week removing my heat exchanger, flushing it with barnacle buster, replacing all cooling hoses, the thermostat and coolant. Still the same performance. I feel pretty positive it’s not the mixing elbow. Two days before I took ownership a new one was fabricated and installed (the previous one developed a hole and was leaking exhaust and exhaust water during the sea trial. Part of deal was for PO to replace before I bought). That leaves me with the prop.
I looked at the paperwork that came with the boat and it looks like the first setting that was tried was 24 degrees (according to the meticulous records the last two POs kept). There is a note in the manual later that says they stepped it down to 22 degrees. I wish I would have found that when I was asked the first time I just didn’t dig deep enough.
So, my plan is to haul out Tuesday, adjust the pitch and splash all within two hours. The adjustment seems pretty straight forward according to the manual and a few videos I’ve watched. I plan to check where it is at and if higher than 22 set it there. My question is for others who may have the same prop. Where is yours set and what kind of performance do you get with that setting. For M35 owners, what are your normal operating temps and where do you cruise for RPM?
Thanks for any help and suggestions guys. Your information is always invaluable.
Hi Kevin, your overheating problem could also be caused by a worn impeller. We had exactly the same symptoms a couple of years ago and it turned out to be an impeller with some vanes missing.
I assume that during sea trials there weren’t any issues with overheating and engine RPM. Your yard then changed something and now you have problems. Why didn’t they set the pitch back to where they found it?
It does seem like a prop problem.
Joe Valinoti
S/V IL Gatto NS30U #221
Sea Harbour YC
Oriental, NC USA
Thanks for all the replies everyone. A couple of things in reply to the replies.
1. I thought maybe the impeller as well. The water pump is a brand new Oberdorfer that I installed last year. Even then I still replaced the impeller while servicing the rest of the raw water circuit. Sorry. I failed to mention that in my first post.
2. To test things, while at the dock in neutral I pushed the throttle slowly to wide open. My tach only made it to 2900 RPM. That's why I assumed 2200 for a cruising RPM. 80% of WOT. According to the post here I should be 3200 or more WOT. Now I'm wondering if might be a tachometer problem. Still, I would imagine I shouldn't be seeing steam when under load. While doing this I pushed to 2200 RPM in neutral and let it go for about 2 minutes. 0 steam. When under load steam is coming out within 1 minute. That's why I feel like it is an overpitched prop.
3. Funny you should mention overheating on the sea trial. When we left the dock the engine was overheating in minutes at idle. Turned out the PO didn't add enough coolant after replacing the mixing elbow. We shut her down immediately, topped it off and no issues. The engine has been looked over by a diesel mechanic and said all seemed fine. The engine was shut down immediately after the alarm went off. I've noticed no issues either other than being limited to 1800 RPM in the year since. During the sea trial all the engine tests passed everything the surveyor put it through including a WOT test for 3 minutes. This was all before the prop was removed.
4. I have no idea why the yard didn't mark the settings on the prop before they pulled it. Like I mentioned I received a call from them when it came time to reinstall asking if I knew what pitch it was set at beforehand. At the time I didn't even know the maxprop COULD be repitched.
So yeah. I agree I really feel like I'm pitched too high. That's why I was curious if anyone else had a maxprop and what settings they were using and how it was working for them.
Thank you to everyone for the insight. I will have a buddy to help out and my wife will be there too. She likes to learn about the boat and get her hands dirty as well. Between the three of us we'll get it figured out. Worst case this boat yard is very familiar with MaxProps. If I screw up I'll suck it up and pay the labor for them to do it. :). I just hate paying someone for something I can do.
FWIW, we were a little under propped using the settings PYI recommended for our 3 blade MaxProp. After using the settings they gave us for one season, we went up one setting on the blade angle. That being said, I think it is unlikely that PYI would have specified settings for your prop that were high enough to result in the performance issues you are experiencing. Seems more likely that the yard botched the re-installation of your prop somehow, maybe by misreading the blade angle to pitch table or by simply setting the prop index marks incorrectly. The MaxProps are great. Once you get it right, you’ll love it. Good luck.
Make sure that your tach is reading correctly. I had a recent survey and the surveyor used an electronic digital tach. My tach was 200 to 600 rpm higher than his depending on speed. It would be a shame to make adjustments to prop pitch due to bad info.
The m35 is rated 30 hp at 3200 rpm,
At full throttle, you should be close to 3200.
If significantly under, you have too much prop pitch or diameter.
I also run at 2400 with a 3 blade flex o fold folding prop
Mark fagelman
N-33 Puff
Hi All,
Has anyone ever had their wishbone hanger cables get caught on the steaming light. This past weekend, I had both get hung up. It appears I need a lower profile one. Any thoughts?
