Hello All,
I know Jefferson Marlago isn't a fast speed boat, but i do know there are a lot of knowledge on this site so I thought to post a thread here and also on THT.
I just recently purchased a 1997 25' Jefferson Marlago with Twin 250 EFI mercury outboards. When I test drove it It had 1/4 tank of gas, 3 guys on board and my phone GPS said 50MPH @5100RPM top speed with cruising in the mid 30's. When I picked up the boat, loaded it with fuel, water and 5 guys I got the top speed at 43MPH @5100 RPM. I am spinning Stainless steel 21 pitch 4 blade props. I thought this boat would be mid 50's but my last run (at the end of the weekend) I was dead empty on fuel with 5 guys and only saw 46 mph. Anyone on this forum have similar or same boat and know what they run? If I drop to a 19 pitch would I see more MPH? How about 3 blade? Any information on how to increase MPH would be very helpful.

Thank you,

Hi,

I would start with calculating your "slip %" using one of the many formulas available on the internet or Mercury Racing website. See what you calculate out to compared to what possibly the manufacturer might tell you or someone else with a similar boat. Then you will know how you stack up against what it should be and you will be able to figure out to either most likely reduce slip or add slip.

Did you mean 35' ? I haven't seen or heard of a 25 they made with twin's. Anyway, probably apples and oranges, but if you go to Yamaha's sight and look up performance bulletins (reports), they have a few tests of the Marlago 35' with some different outboard power configurations, IIRC. I'd love one of those 35's too!

Hello, my name is Justin with Marlago Boats. I have attached the Yamaha performance bulletin for 250 4-Strokes from 2006. The report done by Yamaha produced a top speed of 57 mph with a half load of fuel, standard gear & 2-3 passengers. The FS35 generally does not perform well with most 4-blade props. The best prop to use for your setup would be the 14-1/2'' x 23 Saltwater Series(with no bottom paint). If the boat is bottom painted, the 14-1/2'' x 21 Saltwater Series is needed to compensate for additional drag. Make note that bottom paint typically reduces overall speeds about 4 mph. Please feel free to contact us if you have any other questions, [email protected].

My 2001 Marlago with suzuki 250 4 strokes (622lbs each) with bottom paint has run a best of 53mph on a light load in salt water. It runs around 50mph with a load in fresh water. It's got suzuki props, i think 19's and the lower units have a 2 to 1 reduction, I think.

Damn. I need to get the bottom paint off and get new props!

Please note this is a 35' Marlago. One wrong strike of the key and I don't know how to edit it now. Sorry for the confusion!

3 blade or 4 blade?

3-Blade

I guess I will be in the market for twin 3-blade 21 pitch. I heard I might even need a 19P 3-blade because right now I am running 21P 4-blade.....thoughts?
If I can get the paint off the bottom of the boat (suggestions on how to do this) then maybe i will look into the 23P