Marinette Boat Forum

I had moved my helm forward 18 inches, which shrunk the cabin the same amount. I was able to get an additional 130 gallons of fuel onboard. Now I hold 280 gallons total. I still have some fit and finish to do, but over all it was worth it in my mind. We travel to a National Park that is 70 miles dock to dock, 60 miles of open Lake Superior. The gas out there was $8.62 a gallon last summer. So now I can make a round trip with plenty of reserves and not have to buy fuel over there.

The last few pics were of my Garmin chartplotters showing the speed of 31mph at 3,000 rpm. Getting a 1.3 mpg with a pair of 454 Chevy's.

I also just picked up a set of used Bravo 3 duoprop outdrives that I will install this coming season. After I tear them apart to make sure the internals are good. This should also improve my efficiency.

Don't mind the big hole in top of the dash, it was a temp spot to mount the chartplotter while doing the water test. It has been covered.

I'm thinking something happened to the amount of views on this thread. It was at 10,000 a couple months ago, now it says 2.4 million. Maybe the google algorithm directs them here from the thread title?

TinLizzy wrote: ↑Sun Mar 03, 2024 7:43 pm I also just picked up a set of used Bravo 3 duoprop outdrives that I will install this coming season. After I tear them apart to make sure the internals are good. This should also improve my efficiency.

I am very curious what kind of performance increase these give you.
I have driven many boats with them and know "seat of the pants dyno" the difference is massive.
I have never seen a conversion with before and after specs to see what it actually does.

Tracy, I also am very curious. On a 25 Bayliner flybridge with a single 454, my father switched out a bravo 2 for a 3 about 15 years ago. It gained about 3 to 5 mph at 3200 cruise. Pessimistically I think it will run about 32 to 33 mph at my cruise rpm of 3,000. Optimistically, I will be tickled if it will run about 35 mph. The drives came with 24 pitch props, which may or may not work, I won't know until my first water test. I have a single set of 26 pitch, so I would have to get one more set if the 24's don't work. I pulled the prop shafts out and looked at the gears and bearings and they looked good, so hopefully I can get a few years out of them.