Carver 444 - Compare Data

Do your motors reach peak rpms with no load on? If so the problem is most likely still the propping or possibly the gearing. Were the 24x25 props the suggestion of your yard or was it after a computer analysis by a prop shop?

I believe these motors are rated for 3,000 max RPMs but are often propped to get about 3,100 from what I've read. So it sounds like the motors are fine. If you're getting close to that under load then there is no problem. I used to run the 2002 version of this boat with the small Volvos, and your speeds sound about right (bad but right). Our boat would max at about 17-19kts in calm water. In a 2' sea she'd be down to 12-14kts. The selling point of these boats is the layout, not their performance or sea keeping.
On a side note be careful when fueling those aux. tanks. If you get fuel up into the fuel neck the odor enters the aft stateroom on the port side.

We have a friend in our Marnia with your setup and he has re-prop'd also and gets your results, but he did put bigger tabs on and planes now much ez'r. the factory ones are to small.

You will see a wide range of "theories" for setting factory props depending on the boatbuilder. They typically want to get the highest documented speeds for better sales. Some things that I have seen include setting props at ridiculous light loads and not including margin for owner's gear. This light load does not represent a true weight and trim condition for the owner. Also, if they do these "optimistic" settings in colder climes, they will never translate to high temp and humidity conditions in FL.

Talk to Joel at General Propellor in Bradenton 941.748.1527, as a major OEM prop supplier he has just about seen it all.

There may be other issues at work, including weight/trim, and inefficient tabs. It sounds like your boat sits stern down and can't get out of the proverbial "hole" . I have seen some prop guys play with cup (while reducing some pitch) to get more lift out of the propeller and improve this issue on some boats, but this tends to be a long trial and error experience with multiple haul-outs. Going to the largest (Dual Ram) tab is also a good improvement.

One insurmountable problem you're facing is that this boat is basically designed as a 39 and then extended.

Every Cummins boat I've run with the 330's, 370's, 450's or 480hp has ended up overpropped after they've accumulated 200 hours or so on them......overpropped by about 200 rpms give/take. In my experience it seems the Cummins lose 20% of their power somewhere after the first few hundred hours, then they seem to stay that way for the life of them......I can think of a dozen boats I've run over the years with the above mentioned HP's and they've all been the same......

naw can't tell you the size of his tabs and he's gone for the season. Get a hold of Bennett marine they're great to work with, I'M changing my own tabs this yard period, Carver put 28x9's on my 3607 and upping them to 42x12 with dual rams and water dams on the ends of them, The dam keeps the water under the tab at the ends and makes even more lift.

as for prop's mine started life as 22x22's they're now 22x21 with a #4 cup. it took 3 seasons to get them right. We put the cup in to cut back on slippage.

But remember I'm running 454 Merc's with 1850 hrs....O and they still squeeze test at 160 lbs. avg.

You have diesel engines you get 3200 rpm which is perfect. I look at other carvers like yours with the same engines and they have the 24 x 30 for a prop size. You do have the wrong prop size I would go back with your original prop after the prop shop recondition them. If your engines have a lot of hours on them it might need a overhaul. I also would find a true cummins mechanic to check your engines.

You should have a electric governor on your engines so 3200 rpm is all you would get. Thats why you change your props to a smaller one it only turned so much. If it was gas engines you would see a big difference in your rpm. Look at a 2003 carver and see if they did any changes on the trim tabs, I don't think so.

The No Load 3200 rpm for this diesel is at that dock in neutral, hence No Load, and is indepenedent of prop size. It just verifies throttle travel and the engines ability to hit peak rpm.

One question not asked yet is what is the water depth this boat is running in? I have also seen some boats struggle to get out of the whole in water depths under 12' (ICW), you typically want to sea trial in a water depth of at least 5 x your draft.

I agree with the previous reply in regards to the "published" data being a bit exaggerated....I have been racking my head against the wall trying to get better performance from my 1994 440. With twin Cats 3116 (300 hp) I am turning the published 2800RPM with original props and tabs and still only squeaking out 16.5 kts WOT FULLY loaded.......I am anxious to lighten the load and try again .......so you are not alone !!