Carver Owners Forum

We're going on owning our 1995 325 Aft Cabin for 2 complete years now, and one thing has always bugged me. Our normal cruising speed is about 10 mph. The specs say this is about HALF what it should be. I've never been able to get it up on a plane. I've tried adjusting the trim tabs to different angles with no effect. The bottom paint was new when we got her, and it was repainted last year. She's got Crusader 350 xl's, one of which was replaced last year, when the old one threw a rod, and there's no power difference between the new and old.

RPM-wise, if I run at around 2800, we'll go around 9 mph. Boosting it to about 3200, we'll only break 10-11 mph. Going above that, it's still just fractionally faster. We'll only get up a bit beyond that amount when we've got very favorable currents. Again, Carver's spec sheet says that we should be doing about 25 mph at 3200.

Are there any thoughts on what could cause the difference between the posted cruising/max speeds and what we're actually experiencing? The only other thing I can think of is that a previous owner replaced the props with something a lot smaller than original. But as it'll probably be a while before we pull her out again to check, any thoughts on other things to test/tinker with in the meantime?

Are your tachs reading correctly?
If they are, I'd be looking at those props.

Could be a number of things contributing to poor performance; engines not tuned, wrong props or in need of tuning, too much marine growth on her bottom, excess weight, improper use of trim tabs, etc.

What rpm are you achieving at WOT (wide open throttle) in gear?

Yep…what is your WOT RPM?
When was the last time your boat was hauled and bottom cleaned/painted?

Bottom was painted last October. We took her out right afterwards and got the same speeds.

The port tach definitely needs to be recalibrated, as it is certainly off after the new engine was installed. Starboard seems fine. I haven’t taken her up to WOT in a while, but specs say it should be 4,400, and that feels about where it would be, given where the throttle is at 2,800 and 3,200. And I’ll note that it was having this issue when the old port engine was in there too.

Probably someone over propped it to "save fuel". This doesn't work. You need to see if you can get to rated WOT, even for a few seconds. If not, verify the engines are tuned properly then look at the props.
A friend of mine has a 1999 325 with mercury 350 magnums. His will do 40mph. He actually pulls the kids on tubes with it.

I agree, probably over propped...unless you have a colony of sea lions on the platform ....so considering that and the symptoms you are experiencing, if it were me, I would keep the rpm down to around 1500 until this can be verified and the props checked out. All you are doing is digging a hole and pushing water, which wastes fuel and beats up the engines.

Planing hulls work at two speeds, hull speed, ( for your boat, around 6 to 7mph ), and on plane with the hull on top ( starting around 14 Mph )......between those two is the giant wake behind the boat.

Thekaj wrote:Bottom was painted last October. We took her out right afterwards and got the same speeds.

I hear you, but just an FYI, your running gear can accumulate a lot of barnacle growth since it was painted.
My boat was painted in mid April and I had to pull it out 10 weeks later to clean the running gear as I had lost about 7 knots in that short amount of time.

Just FYI - I have the same engines with V-drives. At 3100 RPM, I get 20mph, which is also my efficiency sweet spot. Usually have fuel tanks full, but very little water onboard. 90 gal of water weighs 500 lbs. My props are 19 X 19. good luck! er

Thanks for all the comments. I'll definitely take her out at WOT next time we're out to see what the RPM range is. By coincidence, I took photos where you can see the props when it got hauled out last Summer, so I've been trying to compare them to props on other 325's. It kind of looks like they might be smaller than the other ones I've seen, but that might just be confirmation bias. Plus, it's not like I can tell the angles via photos from 15 feet away.

And yeah, I've got fuel flow sensors on both engines, so I'm acutely aware of the exponentially poor fuel economy we get as I increase throttle and DON'T get on a plane. There's quite the psychological pressure though to push up the throttle, so as to go just a bit faster, despite the hole it opens up on our bank account. Especially since our last boat was much smaller and could easily do 25 mph. Doing 9-10 mph instead is a very slow moving form of torture.