---

I have a 15" super sport 1988 with a Yamaha Pro 50 hp (2 stroke) has worn out. I'm looking at a new 4 stroke Yamaha in either 40 hp or 50 hp. Both engines are awesome, but wondering if the 40 hp is adequate vs the added cost and weight of the 50 hp? I want to make sure the boat performs well and is not "sluggish" out of the hole with the 40 hp 4 stroke? Yet, i dont need to have 60 mph top end either - mostly easy cruising and some fishing. YAM dealer says the new 40 hp is more than enough for the boat and probably equal or better than the old 2 stroke 50 hp. Any thoughts or experience would be great. The boat was rated at 50 to 70 Hp, but I have heard people with the 70 hp 2 stroke say that the boat is over-powered

---

Your boat is rated up to 70hp.
http://www.whalercentral.com/userphot...lbum_id=44

Most people I see here don't go below 50hp and 60 and 70 is common.
http://www.whalercentral.com/articles...icle_id=77

---

I agree with Joe. I have a 50 2 stroke and I'm happy with it - fast out of the hole and top speed is ~38 with just me When the boat is loaded down top speed is ~35. If I were to repower I would go with the 60 or 70.

---

Your dealer is trying to sell a motor he has in stock rather than ordering you the appropriate motor. Shmuck

Find another dealer.

---

I just repowered my 1995 15 foot Dauntless with a new Yamaha F70 4 stroke. The F70 is new 2 years ago and is Yamaha's new mid range lightweight motor weighing in at 257 pounds which was almost the same weight as the 1995 Johnson 70 HP 2 stroke that it replaced. From my knowledge the Yamaha 60 HP is the same weight if not heavier as it is the old design and was only $500 less when I priced it out against the F70. After a $500 incentive from Yamaha and the trade in for my old Johnson 70 2 stroke, (the Dealer told me he only gave $700 in trade in value), the total price was $8000 for the F70, new controls, shift and throttle cables, tach, speedo, volt meter, trim gauge, and all harnesses and rigging. I have yet to test the boat due to the whether but I am expecting to do so in the next couple of weeks. So, in my opinion saving $500 or $1000 to go down in power from a 70 to a 50 or 60 HP would be penny wise and dollar foolish considering if you are not happy there are no returns on a motor that has already been rigged.

---

If you were happy with the performance of the 2 stroke 50hp when it was running properly, I would buy a 50 or 60hp 4 stroke. The 4 strokes generally have less low end torque. The 40 is going to be slower and have less of a hole shot.

---

I've got a 2004 tohatsu 40hp(2Stroke) on mine. Its no speed demon but it moves the boat okay. It cruises around 19/20knts and tops out around 28knts, with me, the wife, 2 young kids and the dog. I would love to have a 70 on back, but hard to fork over 10k when the current motor does fine.

---

All, Thanks very much for the information and personal experiences - all confirming my same analysis and "gut" that the 50 hp is the best option to take . Love the new 4 strokes for all the obvious reasons, just not sure how they perform vs. the same HP in a 30 year old 2 stroke? I too have seen this boat with 60 and 70 hp engines, but that would be too much power for what I need. Staying with the 50 hp is the best and the 40 hp would probably be sluggish - thanks again. I will send pics when I get the re-power and all the wood refinished and completed!

---

I put a Honda 50 on my 15. Ran great and was economical, but I sure missed being able to go over 30.
Compared to the previous power (85) it was a bit of a disappointment.

IF I had to re-power that boat it would not be with a 50 4 stroke.

---

I second jgortva post. but you seem to have made up your mind to go with the lesser 50HP. You'll hate trying to get onto plane with a load, but you can putt around economical.

---

Actually, you won't necessarily save gas by putting a smaller motor on there. Take a quick look at some of the Yamaha performance bulletins for the 50, 60, and 70 4-strokes. I didn't look at every bulletin by any means, but on a boat called a Sundance FX17, the 70 had the best "putting around" fuel consumption and got only 0.01 MPG less, at cruising speed, than the T60 - and the cruising speed for the T60 was 17.8 MPH vs. the 70's 23.4 MPH. A lot faster cruise, and just as good mileage? I'll take that - and did, with the F70 I have on my 15. And my cruise speed of around 4000 RPM gives me 9 - 10 MPG, about the same as the Sundance - so it seems like a valid comparison.

So by all means go with a 50 if you want to limit top speed (for use by an inexperienced operator, for example) or for the lower purchase price. But don't do it for the fuel savings - there aren't any.

Tim

---

Just a few other data points I found interesting from the Yamaha performance bulletins, comparing the F70 to the F50, again on the Sundance FX17:

Top speed of the F50: 32.0 MPH @ 5800 RPM, 6.67 MPG
Top speed of the F70: 39.5 MPH @ 6300 RPM, 6.27 MPG
F70 matching F50 TS: 32.0 MPH @ 5250 RPM, 7.25 MPG (interpolated from data)

Cruise speed of F50: 23.7 MPH @ 4500 RPM, 8.78 MPG
Cruise speed of F70: 23.4 MPH @ 4000 RPM, 9.36 MPG

So even if you didn't want to ever go faster than 32 MPH, you're getting better mileage with the more powerful motor. That, along with reserve power when running heavily loaded, would be enough to push me to the 70. Might be worth at least looking into the cost difference.

Tim