360 Mariner Performance

[Flott]

I'm looking at buying a Carver 360 Mariner with Crusader 330 hp 5.7FI Captains Choice engines. Absolutely love the boat but the test drive came up with a 20 mph TOP speed per GPS. Tachs were turning at just 4000 RPM which I believe is low. Props are four blade 20 x 21s. Boat had pretty much full fuel and full water and 4 people but otherwise fairly empty. 3500 RPM got us approx 15mph (not Knots) and seemed to be working hard. I was VERY Disappointed.
Anybody out there that could give me comparative numbers from their 350 Mariner (same basic boat) or 360 Mariner Or any suggestions of what might be causing this or better how to improve it. Carver told me that the boat should cruise at almost 20 knots and should top out at 26 - 27 Knots. Comments PLEASE!

[Cooler]

Just 2 cents worth from me. You are pushing 20,000 lbs and I assume you have V-drives. 4000RPM is a little low, but depending on engine hours may not be out of line with 4 blade props. Water conditions also factor in. Is the bottom paint in good shape? These big flat bottoms can get slowed down by junk on hull. Carver is not known for speed with these flat bottom boats. But for me, the room, comfort, and construction value makes up for 5 mph. Good luck. er

[bud37]

Heh there....these boats are not fast....full fuel and water plus 4 people, your numbers sound about right. My guess there may be more with a tune....injectors /plugs...What year ??

Consider the bottom/running gear cleanliness first though as it can really hamper performance.

Remember Carver performance numbers are clean new bottom, hardly any weight ....new engines/props etc.

But I get around 20 knots at around 4000 with a 350 Mariner...6.2 mercs though, same HP...we are also in fresh water. Now when I got the boat, the bottom was fouled a bit , but sped up with use. Personally I have never worried about getting max rpm in any of our boats, we just run em slow.

Good luck with your boat.....

[Flott]

When we pulled the boat I was hoping there was 5 inches worth of crap growing on the bottom of it but that turned out not to be true, it was fairly clean. I'm not that interested in Top speed, I just posted that as an example, but having the engines working hard to do a max cruise of 14 to 15 miles an hour just seemed off.

[Flott]

Carver also told me there was only a 1knot or 2 knot max difference between the 5.7's in the 6.1s.

[denpooch]

Hey Flott. I have a 36 Mariner with Captains Choice 6.0's. I never push above 3400 -3500 rpm's.
Depending on load (people, fuel, water, current, etc.), I am looking anywhere between 16mph - 19+mph. Have not hit 20 yet.
She's certainly not a racehorse but fits my bill perfectly.

[tomschauer]

I'm kind of surprised by those numbers. My 355 with 7.4's likes to cruise about 3200-3400 rpm 23-25 mph and tops out about 31 -32 mph with full fuel and 2 or 10 people on the boat, it doesn't seem to make a difference.. I would think the mariner would be a bit quicker as it has a nearly flat hull with very little deadrise.

[bud37]

Source of the post I'm kind of surprised by those numbers. My 355 with 7.4's likes to cruise about 3200-3400 rpm 23-25 mph and tops out about 31 -32 mph with full fuel and 2 or 10 people on the boat, it doesn't seem to make a difference.. I would think the mariner would be a bit quicker as it has a nearly flat hull with very little deadrise.

The hulls are quite different.....the Mariner has a much deeper entry than yours, even though the aft is quite flat. Something that is really noticeable when they are compared on the hard. Also because of the V drive engine set up, I believe the shaft angles may be a bit steeper.

[denpooch]

One item that I did not mention is the 'windage' factor of my set-up. I have a full Eisenglass bridge enclosure. That MUST slow her down a couple knots. It is likely when speed tested by Carver, she was 'bare naked' up there!

[Flott]

Good points all. Thank you. I'm still a little perplexed but still doing research.