Repowering a classic 1972 Boston Whaler 13 Sport

[Lanti24]

Im repowering a 1972 whaler 13 sport...cutout transom with 15'' shaft


Would you pick a Mercury efi 30 or Mercury efi 40?
Weights are: 172 lbs for the 30, 216 for the 40.

i'm a bit worried to overweight the transom...



All round usage, please help me!
Thanks, all the best

[Velocity72]

I had a 1972 13' with a 2004 40 carbed Merc 2 stroke on it. And it was one of the most fun boats I ever owned. Don't remember the weight of that motor, but the rig was a perfect combo of speed and skiing.

[timmc6]

Im repowering a 1972 whaler 13 sport...cutout transom with 15'' shaft
here is my 13 whaler that i just give away with a 60 hp omc and it did a good job,not sure on weight of 3 cyl omc but it was no problem,tim

Would you pick a Mercury efi 30 or Mercury efi 40?
Weights are: 172 lbs for the 30, 216 for the 40.

i'm a bit worried to overweight the transom...



All round usage, please help me!
Thanks, all the best

they are great little boats

[bigbluechevy454]

I 2.5L should be enough power

[Instigator]

I did a 13' w/a 50 HP carb'd 2 cyl OMC on it. Was a blast to drive fast but off plane it sat very low in the water and have heard many stories about the 4 strokes being pigs on these boats so I'd be careful.
Mine was a 15" transom too and I raised it to 20" to have more motor options. Was about the only way to get power trim which you should consider mandatory on this boat.
When I first hug the 50 it had no trim and was barely faster than the 28 that it replaced. W/the trim added it was 20 MPH's faster.

[Lanti24]

Hi thank you everyone for your suggestion and for the nice pics... i have to decide in a few hours!

I think i want the 40hp even if 216 lbs...
I could counter-balance the boat by putting the tank and the battery forward beneath the bow sundeck... what about this?

These old 50-60 OMC you had dont look that lightweight after all... Are those 737cc. / 45 cubic inches or bigger?

Let me know
Thank you guys

I did a 13' w/a 50 HP carb'd 2 cyl OMC on it. Was a blast to drive fast but off plane it sat very low in the water and have heard many stories about the 4 strokes being pigs on these boats so I'd be careful.
Mine was a 15" transom too and I raised it to 20" to have more motor options. Was about the only way to get power trim which you should consider mandatory on this boat.
When I first hug the 50 it had no trim and was barely faster than the 28 that it replaced. W/the trim added it was 20 MPH's faster.

[Velocity72]

I had the tank and battery in the stern with the 40 Merc and had no problem. It had a 20" transom.

[GIL_CV21]

they are great little boats

those 13 foot whalers are a blast, mine is a little screamer !

[Li'l Toy]

I know that, in the 60's, you had to sand the hook out of the bottom at the transom for best speed. At that time, the boat was essentially a flatbottom. I don't know when they went to the sort-of V bottom, but you may want to see if it has a hook at the very end of the hull.

[sundancekid]

I have repowered several 13s, mostly with the 40 EFIs, they run very nice. With two people and full fuel, it will do 37 mph spinning a 13" SS Vengeance right to 6000 with plenty of hole shot. You definitely want power trim, which the 20 is the only one to offer that in a 15" shaft. I did one with the 25 (same as 30) and not as impressive. With a 11" aluminum, it did 28 with two people and full fuel, which wasn't bad, but it was tough getting on plane with two people unless someone was up front. See pics below with the 40, that's the way to go:

[Lanti24]

Hi Sundancekid thank you for your suggestion...
I see you also kept fuel and battery in the stern,very nice.

i think i'll pick the 40

I have repowered several 13s, mostly with the 40 EFIs, they run very nice. With two people and full fuel, it will do 37 mph spinning a 13" SS Vengeance right to 6000 with plenty of hole shot. You definitely want power trim, which the 20 is the only one to offer that in a 15" shaft. I did one with the 25 (same as 30) and not as impressive. With a 11" aluminum, it did 28 with two people and full fuel, which wasn't bad, but it was tough getting on plane with two people unless someone was up front. See pics below with the 40, that's the way to go: