20hp Yamaha 4stroke for SmokerCraft Big Fisherman?

[MI Friend]

I have an older 16ft Big Fisherman that is in great condition. It weighs 420lbs dry. Now using a 25hp Evinrude 2 stroke. Can run 28mph with one person and 21 mph with 2 people and gear. Want to go to a 4stroke and like the Yamaha. To keep weigth down looking at 20hp which weighs 132 lbs with power tilt as opposed to a 25hp which weighs like 180lbs. Will the 20hp be big enough to get like 20mph? Any thoughts or info appreciated.

[Hula_Grub]

There's a calculator for props on piranha's HSOforum. If you know the WOT of the motor and pitch and diameter of the prop, it will tell you theoretical top speed. Garbage in, garbage out, however, so make sure you use accurate numbers.

I had a bad experience being under-powered with a 4-stroke. Be very careful what you get. Horsepower is used to overcome drag and/or accelerate. Top end speed is more a function of hull design.

I went from 23 mph with 25 hp to 28 mph with 40 hp, which maxed out my boat. But now I can plane out easily no matter how heavy the load I'm carrying.

Good luck!

[Northlander]

Ya if it was me I would be looking at 40 horse in a 4 stroke for a 16' boat. 25 horse if you dont care about getting on plane and top end.

I had a 25 horse 4 stroke yamaha on a 14'er and topped out at 25 mph with 2 people in it and it was slow getting out of the hole.

[jasper60103]

I have an older 16ft Big Fisherman that is in great condition. It weighs 420lbs dry. Now using a 25hp Evinrude 2 stroke. Can run 28mph with one person and 21 mph with 2 people and gear. Want to go to a 4stroke and like the Yamaha. To keep weigth down looking at 20hp which weighs 132 lbs with power tilt as opposed to a 25hp which weighs like 180lbs. Will the 20hp be big enough to get like 20mph? Any thoughts or info appreciated.

I pondered the same decision a while back. I have a 400# tiller boat too and can't see putting that much weight on the back end. I kept my 2 stroke for the time being. I may eventually go to a 4 stroke if I get a console steer boat.

[Tullibee]

For what its worth to you, my buddy has an old 16' Lund that he cut the middle bench out of and put a plywood floor and casting deck in. Not sure how much it weighs but I would guess its pretty comparable to an older Lund Rebel which tips the scales at 455 lbs.

He has a 20 hp Tohatsu 4 stroke on it that weighs 114 lbs. I was skeptical on how this motor would push this boat, but was pleasantly surprised that it planes her out even with 3 dudes and gear.

Granted a 25 would be a better setup for this boat but he couldn't justify spending an extra $2000 dollars to have an extra 30 to 50 lbs. on the transom.

Cory

[MI Friend]

Thanks for the comments! Please keep them coming! I spoke to one dealer and he said no problem if I keep the load to 2 people and not a big bunch of gear. He is a Smokercraft dealer. The other dealer said the 20hp 4stroke is like -30% of my old 25 2 stroke and thinks the 20 too small. The question contiues. Anyone out there have a 420lb boat with a 20hp 4stroke? Must be someone or who knows of someone?