Yamaha 115-HP Four-Stroke: Poor Acceleration

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Author Topic:   Yamaha 115-HP Four-Stroke: Poor Acceleration

blacksmithdog posted 06-05-2006 12:32 PM ET (US)
We were just out this past weekend on Lake Moultrie in SC. We were in our 1976 Montauk with a 90-HP Evinrude two-stroke. Our friends were in a 17 Sea Hunt with a 115-HP Yamaha four-stroke. The boats weigh approximately the same. I was very surprised at how slowly the other boat [accelerated], primarily pulling a skier. The Boston Whaler [accelerated] considerably faster. Do some four-stroke outboard motors [accelerate] faster than others?
kglinz posted 06-05-2006 01:26 PM ET (US)
YES
bostonbill posted 06-05-2006 01:32 PM ET (US)
Two-Strokes are your best performers when pulling and skiing. [Acceleration is] quicker and more powerful. However, if you are just riding, cruising or fishing, the fuel economy and quietness of a four-stroke is hard to beat.
Safe Boating!
acseatsri posted 06-05-2006 07:49 PM ET (US)
It could also be that the propeller has too much pitch for skiing. A propeller that's great for cruising and speed usually [suffers] when it comes to pulling a skier.
jimh posted 06-05-2006 08:04 PM ET (US)
There is a wide variation among outboard motors in terms of how sophisticated the engine design and how much attention has been paid to optimizing performance. It is difficult to make a blanket statement regarding the performance of various engines.
elaelap posted 06-06-2006 11:55 AM ET (US)
Oh man...this again. Don't get me started.
Tuco (1988 Outrage 18, Yamaha F115 EFI, 730+ flawless swift quiet smokeless economical instant start hours in the past 2.5 yrs, Pacific Ocean north of San Francisco...guess I'm lucky I don't have this pitifully underpowered rig on a warm brown water lake in South Carolina)
pasino posted 06-08-2006 05:12 PM ET (US)
Hi,
i don't know about Sea Hunt, but I have a 1980 Montauk with a yamaha 115 efi that plane in 3.2 seconds.
I also have a friend with a 1990 montauk with a evinrude 90 (ficht?) and my four stroke have much more acceleration, and speed.
Two strokes are better performers, but between 90 hp and 115 there is no challege.
Pardon my english
pasino
BOB KEMMLER JR posted 06-08-2006 07:00 PM ET (US)
I was on my friends 17 pathfinder with a yammy 115 2 stroke and it was a dog too.Could be a mis prop or the label "Yamadog" is a earned one?
high sierra posted 06-08-2006 10:23 PM ET (US)
Tony ,perhaps you could tell them just how fast a 115 four stroke can be on a 170 Whaler. I believe mine is fast enough as is , 48.9 on GPS. Acceleration is not bad either. high sierra
elaelap posted 06-09-2006 01:02 AM ET (US)
Yeah, h.s., every person who has taken a cruise in my Outrage 18 since I repowered with a Yamaha F115 has remarked at how surprised they are at the boat's acceleration (on plane in 3 seconds). Now it won't pitch you back over the transom like a 150 two-smoke, but it gets my boat up to 40+ mph, and I've got her loaded down with a kicker, twin batteries, all kinds of safety gear, two anchors--one with chain--and 70 or 80 pounds of lead salmon weights, plus I always keep the 63 gallon fuel tank full or near-full, and carry another six gallons for the kicker. I've recently 'geared-down' from a 19 inch pitch prop to a 17-incher, and old Cetaceous seems even a little quicker up to around 4800 turns, when in truth she becomes a bit sluggish up to 5900 rpm WOT.
Some VERY experienced and knowledgeable Whaler owners and operators, including Joe Kriz, after driving my boat have expressed their satisfaction with the Yami F115/classic OR 18 combination as regards performance. As for me, I wouldn't trade straight across for a 150 with similar hours even if no money were to change hands. What can I say...730+ very pleasant, economical hours in two and one half years with that rig, and not one complaint, not one problem, just a whole lot of fun on the Pacific Ocean in my Whaler.
Tuco
delucat2 posted 06-13-2006 04:30 PM ET (US)
Remember folks - propellers move boats - NOT ENGINES. The propeller does not care what kind of fuel is used or how it is burned, only that it gets the twist it needs. If a boat is slugish out of the hole or pulling a skier - there is too much prop on the boat. 90 hp from a 2 stroke, DFI, e-tec, or 4 stroke all feel the same to the propeller. Only the speed at which that power is available changes with the particulars of the engine.
Proping small craft with greatly variable loads (skier, 1 vs. 4 people, bait tank, fuel, etc) is not easy. Better to choose a 17 inch (or smaller than the dealer selling speed tries to put on) and be able to pull any weight in any conditions and have the engine last for 10 years than to be able to reach 45 kts vs 40 and burn a hole in a piston at 50 hours.
People buying boats with modern Yanmar, Cummins and Volvo motors are learning this the hard way ($25,000 for an engine!) when the boat that they seatrialed new that did 27 Kts now after you have added 3000 lbs of goodies and fuel and water and wife now only does 23Kts. Most of the time you are lugging the engine and they go POP! to the tune of huge dollars. Loosing 2 - 3 inches of propeller on many of these boats is necessary to get them in the proper groove. Unpopular when speed sells, but better than wasting a very expensive engine. Same rules apply here.
zaffo

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Author	Topic: Yamaha 115-HP Four-Stroke: Poor Acceleration
blacksmithdog	posted 06-05-2006 12:32 PM ET (US) We were just out this past weekend on Lake Moultrie in SC. We were in our 1976 Montauk with a 90-HP Evinrude two-stroke. Our friends were in a 17 Sea Hunt with a 115-HP Yamaha four-stroke. The boats weigh approximately the same. I was very surprised at how slowly the other boat [accelerated], primarily pulling a skier. The Boston Whaler [accelerated] considerably faster. Do some four-stroke outboard motors [accelerate] faster than others?
kglinz	posted 06-05-2006 01:26 PM ET (US) YES
bostonbill	posted 06-05-2006 01:32 PM ET (US) Two-Strokes are your best performers when pulling and skiing. [Acceleration is] quicker and more powerful. However, if you are just riding, cruising or fishing, the fuel economy and quietness of a four-stroke is hard to beat. Safe Boating!
acseatsri	posted 06-05-2006 07:49 PM ET (US) It could also be that the propeller has too much pitch for skiing. A propeller that's great for cruising and speed usually [suffers] when it comes to pulling a skier.
jimh	posted 06-05-2006 08:04 PM ET (US) There is a wide variation among outboard motors in terms of how sophisticated the engine design and how much attention has been paid to optimizing performance. It is difficult to make a blanket statement regarding the performance of various engines.
elaelap	posted 06-06-2006 11:55 AM ET (US) Oh man...this again. Don't get me started. Tuco (1988 Outrage 18, Yamaha F115 EFI, 730+ flawless swift quiet smokeless economical instant start hours in the past 2.5 yrs, Pacific Ocean north of San Francisco...guess I'm lucky I don't have this pitifully underpowered rig on a warm brown water lake in South Carolina)
pasino	posted 06-08-2006 05:12 PM ET (US) Hi, i don't know about Sea Hunt, but I have a 1980 Montauk with a yamaha 115 efi that plane in 3.2 seconds. I also have a friend with a 1990 montauk with a evinrude 90 (ficht?) and my four stroke have much more acceleration, and speed. Two strokes are better performers, but between 90 hp and 115 there is no challege. Pardon my english pasino
BOB KEMMLER JR	posted 06-08-2006 07:00 PM ET (US) I was on my friends 17 pathfinder with a yammy 115 2 stroke and it was a dog too.Could be a mis prop or the label "Yamadog" is a earned one?
high sierra	posted 06-08-2006 10:23 PM ET (US) Tony ,perhaps you could tell them just how fast a 115 four stroke can be on a 170 Whaler. I believe mine is fast enough as is , 48.9 on GPS. Acceleration is not bad either. high sierra
elaelap	posted 06-09-2006 01:02 AM ET (US) Yeah, h.s., every person who has taken a cruise in my Outrage 18 since I repowered with a Yamaha F115 has remarked at how surprised they are at the boat's acceleration (on plane in 3 seconds). Now it won't pitch you back over the transom like a 150 two-smoke, but it gets my boat up to 40+ mph, and I've got her loaded down with a kicker, twin batteries, all kinds of safety gear, two anchors--one with chain--and 70 or 80 pounds of lead salmon weights, plus I always keep the 63 gallon fuel tank full or near-full, and carry another six gallons for the kicker. I've recently 'geared-down' from a 19 inch pitch prop to a 17-incher, and old Cetaceous seems even a little quicker up to around 4800 turns, when in truth she becomes a bit sluggish up to 5900 rpm WOT. Some VERY experienced and knowledgeable Whaler owners and operators, including Joe Kriz, after driving my boat have expressed their satisfaction with the Yami F115/classic OR 18 combination as regards performance. As for me, I wouldn't trade straight across for a 150 with similar hours even if no money were to change hands. What can I say...730+ very pleasant, economical hours in two and one half years with that rig, and not one complaint, not one problem, just a whole lot of fun on the Pacific Ocean in my Whaler. Tuco
delucat2	posted 06-13-2006 04:30 PM ET (US) Remember folks - propellers move boats - NOT ENGINES. The propeller does not care what kind of fuel is used or how it is burned, only that it gets the twist it needs. If a boat is slugish out of the hole or pulling a skier - there is too much prop on the boat. 90 hp from a 2 stroke, DFI, e-tec, or 4 stroke all feel the same to the propeller. Only the speed at which that power is available changes with the particulars of the engine. Proping small craft with greatly variable loads (skier, 1 vs. 4 people, bait tank, fuel, etc) is not easy. Better to choose a 17 inch (or smaller than the dealer selling speed tries to put on) and be able to pull any weight in any conditions and have the engine last for 10 years than to be able to reach 45 kts vs 40 and burn a hole in a piston at 50 hours. People buying boats with modern Yanmar, Cummins and Volvo motors are learning this the hard way ($25,000 for an engine!) when the boat that they seatrialed new that did 27 Kts now after you have added 3000 lbs of goodies and fuel and water and wife now only does 23Kts. Most of the time you are lugging the engine and they go POP! to the tune of huge dollars. Loosing 2 - 3 inches of propeller on many of these boats is necessary to get them in the proper groove. Unpopular when speed sells, but better than wasting a very expensive engine. Same rules apply here. zaffo