another repower question...

2182 · #1 04-21-2009, 08:10 AM

wondering if anyone has numbers for a f150 yamaha on an 18 footer. if not 18 then a 20 footer, weight not being all that much different. have been toying w/ a repower for the last year or so and can get a decent deal on yammis (relatively speaking anyhow). also, would the 200 hpdi just be overkill on that boat? i have an older 200 merc offshore now and have been spoiled by the extra power...any thoughts or ideas would be appreciated. i know there are not a lot of 18s on this website; if you have an 18 w/ any recent repower and could post any numbers i would greatly appreciate it. thanks

HatTrick · #2 04-21-2009, 09:18 AM

I have a 1986 20" CC with a 2005 f150 yami. At 5000 rpms I go 40-41 mph on the gps. I don''t have trim tabs, I do have an alum prop, and I don''t have the fuel usage electronics package. Fuel tank is 70 gals and even with 3-4 ppeople on board and no trim tabs this motor gets the boat on plane quickly. Hole shots don't concern me and high speeds are not commonly attainable in Buzzards Bay due to the conditions we see. Weight is the only drawback to this motor, it has a lot more power than my tired old 1986 Merc black Max did. Overall I am extremely happpy with this motor.

Keyscruz · #3 04-21-2009, 09:22 AM

My 18 has a bracket w/ 22" setback and an etec 150. Prop is 14.5x19 alum 3blade. Speed at wot w/ full fuel is 50mph.

76Red18 · #4 04-21-2009, 01:28 PM

1976 18' heavy loaded, big t top and light weight (375 lbs)carbed 99 150 Johnson 60 degree block w/ 2.25 lower unit ratio running a 15 x 17 3 blade. Planes at about 12 mph with full tabs, cruise 3500rpm @ 27 mph, WAOT 5900 rpm @ 42mph. I would opt rebuild the old jonny before hanging a heavy new motor on it.

Bushwacker · #5 04-21-2009, 11:00 PM

The one metric you should keep an eye on with a heavy motor is min planing speed. These boats will plane at 12 mph with a 300-375 lb motor because that's what they were designed for. Mine will even do that with the 427 lb E-Tec and a 30" setback bracket, but it took a stern lifting prop and Doelfin to do it. A 500 lb motor will probably hurt min planing speed and ride.

A 150 is plenty of power - my Seafari, which is several hundred pounds heavier than the cc's, will run low-mid 40's with very heavy load and all the canvas up. Will hit almost 50 with light load and the top down. Will average 4 mpg heavy, 5 mpg light at about 3700/27 mph.

2182 · #6 04-27-2009, 02:20 PM

thanks guys. im hoping my merc lasts forever but the previous owner yanked a bunch of stuff of it so shes a bit finicky. when shes running strong itll go low-mid 50s but i rarely push it that hard. it is nice to be able to outrun a storm (or a skiboat) when need be though.