Prop me up

[Hayden Sias]

I have a 1998 searay 310 with vdrives which I love. I am 99% sure the props are not stock. They are currently 4 blade. Aren't they supposed to be 3 blsde? I do not know the diameter or pitch but i have reason to believe they're the reason I top out at 3800rpm? What is the stock prop diameter and pitch? I have good maneuverability currently.

 

[Lazy Daze]

There's a prop matrix on SR's site in the owner's section that you can look at - but I'm sure 3-blade would have been standard. However, they aren't "supposed" to be - they can be anything you want.

How long have you had the boat and how long has the 3,800 RPM been going on? It's logical to think that a previous owner changed the props for better performance. But it wouldn't make sense the PO would have settled with the low RPM. Which means, logically, there's another explanation... tune-up items, old gas, low compression, etc.

But, you should find out the prop info.... take a deep breath.

 

[Chip S]

What engines do you have? The 260 hp engines had 16 x 16 3BC props (4800 rpm WOT) and the 300 hp engines had 16 x 17 3BC props (5000 rpm WOT). The 1998 Sea Ray prop chart is at https://owners-resources.searayweb..../1998 Sport Boat Sport Cruiser Prop Chart.pdf .

 

[play dough]

"But it wouldn't make sense the PO would have settled with the low RPM."

I wouldn't necessarily buy that. The chat rooms are full of boat owners that feel a prop change is the magic pill to improve performance without any knowledge of their current rpm range. "I want to improve hole shot." "I want to increase top end." The list goes on. But you are correct there is a laundry list of items that might affect WOT rpm. In this case, I'd start with the knowledge of the 4 blade diameter and pitch and compare that to the factory supplied prop spec. That would at least give an indication that the previous owner took into account the 4th blade when making that switch and then go from there.

 

[Lazy Daze]

I wouldn't necessarily buy that. The chat rooms are full of boat owners that feel a prop change is the magic pill to improve performance without any knowledge of their current rpm range. "I want to improve hole shot." "I want to increase top end." The list goes on. But you are correct there is a laundry list of items that might affect WOT rpm. In this case, I'd start with the knowledge of the 4 blade diameter and pitch and compare that to the factory supplied prop spec. That would at least give an indication that the previous owner took into account the 4th blade when making that switch and then go from there.

I agree that we sometimes fight the PO (previous owner) syndrome - I'm well aware of that ailment! But given that 3,800 is SO much lower than spec, it just doesn't jive with the norm. The props would have to be many "inches" in pitch higher than spec to drop that many RPM's - and it still wouldn't make sense as that boat would take forever to plane off. Possible, yes... but that's really out there with the PO syndrome!

Either way, first step is to ID the current props.

 

[Pirate Lady]

“Besides the jukebox if I die”. Sorry, had to go there.

 

[Hayden Sias]

Thanks for the answers guys. I had the engines tuned up last year. My flame arrestor on my port engines waa severely clogged as a result my engine loaded up eventually fouling all of my plugs. I always thought that would have been tune up 101. Therefore I did not bother to look at them. Anyway,they're both clean,....we did a compression check on all cylinders and they were in the 150 to 155psi range which is ideal for 5.7s. I do use cheap gas but I go through it quick so I don'tmind. If i moved the boat twice a year I would use premium nonethanol. At the end of the year I fill my tanks with premium and seafoam them then run them to get the seafoam into the entire system. I and my mechanic are pretty sure it's props. He feels the engines have more in them. I am not necessarily interested in top end or holeshots. I want the engines to run as intended. I always assume the R&D manufacturers put into their designs are pretty optimal. If I am wrong let me know?

 

[dwna1a]

A great many things can effect performance and top ends. While I agree with the members above there are a few other things to look at. Weight or even how you have the boat loaded. Tuneups, complete ones. Sounds like the PO wanted a better hole shot and sacrificed top end performance. Who knows.

The two best prop companies to call, Michigan Wheel and Black Dog.

 

[Black Valkyrie]

Look at the prop matrix and compare to what is on your boat