Newbie with a Hunter 33.5 Questions

[drummer3278]

Hello,

Just purchased a 96 Hunter 33.5. My wife and I are in awe, as we upgraded from a Columbia 8.3. The previous owner took care of it very well, and the survey checks out near perfect.

As I've poked around on this site, I've come to the conclusion that my boat is a bit slow under power. It has the 29hp motor, which is running excellent (1600 hrs). My GPS shows 5.2 kts, at 3000 rpm on a smooth windless surface. The boats bottom is clean.

It has a bit of a vibration at lower rpm's, but is completely smooth as it gets over 2000.

Here's my question(s). Would a 3 bladed prop give me more speed, or is there something else I need to look at? Where's the best place (online) to get a prop? I live in Bellingham Washington, and is there someone in this area that is recommended? What is the ideal rpm for fuel consumption/speed/longevity of motor?

Thanks in Advance!!

 

[Ralph Johnstone]

I'd Have to Agree .....................

It has the 29hp motor, which is running excellent (1600 hrs). My GPS shows 5.2 kts, at 3000 rpm on a smooth windless surface. The boats bottom is clean.

.................. that 5.2 kts. is a little slow with that HP. As this is SOG from your GPS, have you compensated for current, as we get some good ones around these parts. ?

To get any kind of idea of what's going on, we'd need to know a little more about the pitch and diameter of your prop (stamped on the prop). Transmission ratio is also required. Engine RPM from an optical tachometer would also help as many engine tachs are not reliable.

Given that everything else is in good repair, my "GUESS" would be that you're underpropped. For a crude test, try going to your maximum RPM and see if you get any smoking.

Going to a properly sized 3 bladed prop as compared to a properly sized 2 bladed prop wil NOT give you a significant increase in speed. Just cuts down on the slippage slightly.

However, a three bladed prop will cut down on vibration significantly as only one blade at a time enters your keel wash AND seeing as how you may have prop issues, now may be the time to visit a competent prop shop to look at a three bladed prop. Not much of a compromise seeing as our winds are limited.

 

[Benny17441]

Two things to check, first the accuracy of your tachometer and the fuel lever linkage to verify that the throttle moves to wide open when the lever is pushed all the way. Diesel engines run more efficiently when hot so running at 85 to 90% of maximum rated RPM would yield the best results as far as fuel efficiency for encountered conditions and longevity of motor. The 3HM engine if that is what you have is rated for 3,200 RPM. Do you know how many hours are on the engine or have you noticed if it smokes a little? You can check the valve lash and make sure the mixing elbow don't have much carbon build up. High hour engines may loose some of its power which in turn decrease their ability to push a particular prop. A 3 blade prop will provide smoother performance but will increase drag when the boat is under sail.

 

[drummer3278]

Thanks Benny & Ralph

I will check the prop when I haul out in the spring. The motor has 1600 hrs, and does not smoke at all, even with the throttle wide open. I'm guessing that the factory tach is off, so I will have that checked. The speed of 5.2 knots is flat calm, no current.

Thanks for the info on the 3 bladed prop.