Opinions on if I should repower 18

[bmajvi]

Not sure I've heard much in the way of negatives from guys who have actually owned and run an 18 with a 140? I put a DF140 on my 18' (was really shopping for a Yamaha 115, but got a crazy deal on the Zuke) way back in '02, and was very happy with it. True, it's a lot of weight hanging off the back, and washboards are advisable to keep water out when backing. I can't recall the specs on the prop we settled on (sold the boat in '07), but we tried a bunch and ended up propping for all around performance. Great hole shot, 42 mph in flat water, phenomenal "guts" at any speed, even with full tanks, four (or more) adults, dog, cooler, etc., and absolutely sipped gas. I'll admit that it was more power than I needed or used 90% of the time...I'm sure a 90 would work fine, but it was really nice having the extra juice available when going in or out of a rough inlet with a heavy load. I remember thinking that it was a little like driving a turbo Porsche - everybody best be holding on when you put your foot in it! I do miss that darn boat...

[Bandit91]

Originally Posted by bmajvi

Not sure I've heard much in the way of negatives from guys who have actually owned and run an 18 with a 140? I put a DF140 on my 18' (was really shopping for a Yamaha 115, but got a crazy deal on the Zuke) way back in '02, and was very happy with it. True, it's a lot of weight hanging off the back, and washboards are advisable to keep water out when backing. I can't recall the specs on the prop we settled on (sold the boat in '07), but we tried a bunch and ended up propping for all around performance. Great hole shot, 42 mph in flat water, phenomenal "guts" at any speed, even with full tanks, four (or more) adults, dog, cooler, etc., and absolutely sipped gas. I'll admit that it was more power than I needed or used 90% of the time...I'm sure a 90 would work fine, but it was really nice having the extra juice available when going in or out of a rough inlet with a heavy load. I remember thinking that it was a little like driving a turbo Porsche - everybody best be holding on when you put your foot in it! I do miss that darn boat...

Thanks for the info. Just curious did your boat have the original 20” transom height or had it been raised to 25”?

[Bandit91]

Originally Posted by Beaver

I’d do the 90. There are several guys on this site that have mentioned the 140 being too much weight. The Potter hulls do a lot better with a lighter motor (20” transom and they’re all a little ass heavy). It’ll plane a lot quicker and be able to keep it on plane at a lot lower speed.

I keep waiting for someone to put an F70 on an 18. I bet it would push it fine

Thank you for this info. I am really considering the 90. Just a little nervous spending that much money when I’ve never been on a seacraft 18/20 with that size power.

[Bandit91]

Another thing I found interesting in my research of the 140 is that the weight is less than the older df140s. The earlier 140s were listed at 410 lbs for a 20” shaft and the current df140a 20” is listed at 395 lbs. don’t know how accurate this is but 15 lbs is pretty significant.

[DonV]

Originally Posted by Bandit91

Thank you for this info. I am really considering the 90. Just a little nervous spending that much money when I’ve never been on a seacraft 18/20 with that size power.

Your call, however a 90 might be perfect for just you in the boat. Ya gotta think how you are going to use the boat, how many people, how much gear, coolers and ice, etc., as you add weight the performance will suffer if you're underpowered. Good luck!

[uncleboo]

I ran a '02 df140 for 8 years. I thoroughly enjoyed the power and performance and loathed the heavy ass end. What bothered me the most was that anything under 3100 rpm s and the boat would slowly fall off plane. I read all the threads on engine height and decided to move mine up a couple holes and discovered the transom was toast, soaked toast! That's what coaxed me into doing the transom and floor. Only got to splash it once after completing the work for about 30 minutes before the motor crapped out. However, after removing all the weight, she sits high and planes at very slow speed. Didn't get to run it long enough to stretch it out. Hopefully my NEW df140 will be in this week and I can give some more accurate performance numbers. BTW, mine was a 20" but I raised it 3" and installed a 3" set back jackplate for fine tuning without removing the motor. Good luck whichever way you go!

[Bandit91]

Originally Posted by DonV

Your call, however a 90 might be perfect for just you in the boat. Ya gotta think how you are going to use the boat, how many people, how much gear, coolers and ice, etc., as you add weight the performance will suffer if you're underpowered. Good luck!

That’s a great point, I do agree a 90 would probably be perfect if it was just me in the boat. Thank you for your help

[Bandit91]

Originally Posted by uncleboo

I ran a '02 df140 for 8 years. I thoroughly enjoyed the power and performance and loathed the heavy ass end. What bothered me the most was that anything under 3100 rpm s and the boat would slowly fall off plane. I read all the threads on engine height and decided to move mine up a couple holes and discovered the transom was toast, soaked toast! That's what coaxed me into doing the transom and floor. Only got to splash it once after completing the work for about 30 minutes before the motor crapped out. However, after removing all the weight, she sits high and planes at very slow speed. Didn't get to run it long enough to stretch it out. Hopefully my NEW df140 will be in this week and I can give some more accurate performance numbers. BTW, mine was a 20" but I raised it 3" and installed a 3" set back jackplate for fine tuning without removing the motor. Good luck whichever way you go!

I’m interested to see your numbers with the new motor. What did you do to remove weight on your transom and floor rebuild? Composites instead of wood?

[mikeyk]

Originally Posted by Beaver

I’d do the 90. There are several guys on this site that have mentioned the 140 being too much weight. The Potter hulls do a lot better with a lighter motor (20” transom and they’re all a little ass heavy). It’ll plane a lot quicker and be able to keep it on plane at a lot lower speed.

I keep waiting for someone to put an F70 on an 18. I bet it would push it fine

Bought my 18 that had a tired 96 115 Yamaha 2-stroke. Replaced it with a new 2018 Yamaha F90 4-stroke that I got on a can't pass up deal. Why? I'm on the West Coast where I do quite a bit of 2 kt salmon trolling and breathing 2-stroke fumes on a downwind tack is not the most pleasurable experience. The Pacific has typical running conditions consisting of swells with 12 to 20 second intervals as well as short interval head-high wind swells. There are only a few days when you could run a sustained 30+ kts. comfortably and safely on this short, beamy hull, so right now I'm not missing the potential advantages of 115 to 140 hp that can be applied to this hull.
This is still the ass-heaviest outboard boat I have ever owned, and I'm still trying to adjust to water washing over the transom while sitting in a chop or backing down. I did relocate the battery from the starboard rear compartment to the front of the console and religiously keep the baitwell free of water when not using it
BTW, the F70 and F90 are exactly the same in terms of weight, dimensions, etc. Only difference, I believe, are the stickers and ECU...and the price.

[uncleboo]

Originally Posted by Bandit91

I’m interested to see your numbers with the new motor. What did you do to remove weight on your transom and floor rebuild? Composites instead of wood?

Yes, yes and yes. Check out my thread 'deck replacement'.