Prop Slipping?

[CarreraDan]

Guys,
Yesterday was the first time we have had a group of people on the boat this year--four adults and two kids and I noticed something different. Normally we only have three people on board, approx 500 lbs, yesterday 900lbs. When I was pulling adult skiiers every once and a while it felt as if the boat was slipping, a slight jerking, or a very slight pulsation. You had to be driving to notice this as my passengers were totally unaware of it, the RPM guage was holding steady. My mother in law said she felt it too while I was slalom skiing. I did not feel it when the kids were skiing, tubing or kneeboarding as they were under 100lbs each. I have only felt this slip one other time and that was when the boat was brand new and I had the trim too high and tried a holeshot. The prop is orginal and looks to be in great shape, nothing was wrapped around it, no nicks, dents, etc. The drive shifts smoothly with no clunking, griding, etc. I am thinking this a prop hub problem? Been wanting to get a 5 blade for a while, looks like I might have an excuse. Gear oil is only 30 hours old, looks great. Boat is a 2004 185 with the 4.3 alpha one, has approx 250 hours. I did notice this morning if you pull back on the prop away from the drive there is maybe 1/16 inch of play--I don't know if I have ever noticed that. Any ideas, one of the guys yesterday is seriously wanting to buy the boat and I have a bad case of 10 footitis.

 

[BonBini]

You may have just cavatated the prop some.

1/16 play is no big deal. Some will have an 1/8 or better.

 

[aqua*holic]

I agree. Sounds like cavitation. If this was a spun hub, the RPM's would increase without an increase in boat speed. I am sure you can still find an excuse to get the 5 blade! Although I keep hearing Smart Tabs give a better performance increase than more prop blades...

 

[Gunn]

Ventilation/Cavitation here too; with a large load, and a lot of throttle you probably ventilated the prop by sucking in some air and exhaust gases. Like you said, it's the same effect when trying to start out quickly with the drive trimmed up (did that once too!). You would normally see an increase in RPM, but it probably wasn't enough to register; but it easily felt seat-of-the-pants... I doubt there's anything wrong with your prop. But you may want to increase your pitch a size to give you a better hole shot for watersports. You'll lose a bit of top-end speed, but probably don't care...

Tom

 

[CarreraDan]

Thanks guys,
I will be out on Sunday with our normal load and see if it happens again if the weather is good. I tend to always be worried about potential problems as I grew up with an antique Mastercraft that always had some issue. In the 7 years with the Sea Ray I have only had one minor glitch, the oil pressure sender went out and made a mess in the bilge. $35 and 20 minutes we were good to go again. I was hoping to have a valid excuse for the high 5 as I am growing tired of the less than steller hole shot on the slalom--growing up with an inboard spoiled me. Thanks again,

Daniel