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Old 05-31-2018, 06:49 AM   #1
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Decisions..2007 Yamaha 2 stroke or 2018 Tohatsu 4 stroke

So what would you buy:

2007 25HP Yamaha 2 stroke 10 hours like new $2300 109 LBS
OR
2018 Tohatsu 20HP 4 stroke New 5 year warranty or $2900 97 LBS

Dinghy is a Achilies 315DX 10.6 foot RIB.

I live in Florida and planning to do the Great Loop next year in my 32 Grand Banks.

Can't decide which motor to buy. What do you all think?

Thanks so much for your thoughts.
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Old 05-31-2018, 07:04 AM   #2
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I do love Yamaha but having switched to a 4 stroke, they are so much quieter and no stink. That combined with a new motor with warranty, I would have to go with the Tohatsu. HP on either should be lots for that size RIB.
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Old 05-31-2018, 07:09 AM   #3
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I’d go with the 20 hp which is the rated max hp for the dinghy. We have the same dinghy and ran a 15 hp Yamaha 2 stroke for 6 years. It would easily get up on a plane with 3 adults and some gear. Rarely did we run wot. It was almost scary on how fast it was. We now run a 9.8 Tohatsu 2 stoke and that will easily plane with 2 adults and a dog. Three adults and it takes some work.
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Old 05-31-2018, 07:45 AM   #4
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I think emotionally I lean towards the Yamaha....just old school simplicity.
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Old 05-31-2018, 09:25 AM   #5
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Quote:
Originally Posted by Reel Grace View Post
So what would you buy:

2007 25HP Yamaha 2 stroke 10 hours like new $2300 109 LBS
OR
2018 Tohatsu 20HP 4 stroke New 5 year warranty or $2900 97 LBS

Dinghy is a Achilies 315DX 10.6 foot RIB.

I live in Florida and planning to do the Great Loop next year in my 32 Grand Banks.

decide which motor to buy. What do you all think?

Thanks so much for your thoughts.
I was having a hard time with the fact that you show Yamaha as being heavier than the Tohatsu and looked it up - the specs show the Tohatsu at 115 lbs for the short shaft and the 25 Yamaha short shaft at 60 lbs. If weight is an issue you might want to check those specs out again.
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Old 05-31-2018, 09:28 AM   #6
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Outboard tech continues to improve, parts become harder to source after 10 years. I would choose a 2018 Tohatsu over 2007 Yamaha.
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Old 05-31-2018, 09:35 AM   #7
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I was having a hard time with the fact that you show Yamaha as being heavier than the Tohatsu and looked it up - the specs show the Tohatsu at 115 lbs for the short shaft and the 25 Yamaha short shaft at 60 lbs. If weight is an issue you might want to check those specs out again.
I agree the weight is strange
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Old 05-31-2018, 09:40 AM   #8
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Id choose the Tohatsu. Ive had fewer issues with 4-stroke engines than 2-stroke engines. However, I hate outboards anyway. Given you want to do the loop, Id go with the newer engine under warrantee as the dinghy will likely be important for your trip.

BTW, I think the OP had the weights reversed on the engines.
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Old 05-31-2018, 10:00 AM   #9
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Originally Posted by Reel Grace View Post
So what would you buy:

2007 25HP Yamaha 2 stroke 10 hours like new $2300 109 LBS
OR
2018 Tohatsu 20HP 4 stroke New 5 year warranty or $2900 97 LBS

Dinghy is a Achilies 315DX 10.6 foot RIB.

I live in Florida and planning to do the Great Loop next year in my 32 Grand Banks.

Can't decide which motor to buy. What do you all think?

Thanks so much for your thoughts.
The 2 stroke will be faster & plane quicker.
The 4 stroke will be quieter , leave no water sheen, and use less fuel.

I believe either will be on the higher side for a 10.6 length RIB.
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Old 05-31-2018, 10:22 AM   #10
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4 stroke. I like that my Honda can idle for hours with no smell, starts immediately and is quiet. My wife is legally blind but pilots my dinghy at idle to get chores done. At idle the boat moves at a walking speed and she can't overrun her vision.

If speed and weight are more important, go with the Yamaha.

That's way too much money for an '07 by the way.
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Old 05-31-2018, 10:23 AM   #11
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The 2 stroke will be faster & plane quicker.
The 4 stroke will be quieter , leave no water sheen, and use less fuel.

I believe either will be on the higher side for a 10.6 length RIB.
I have that dinghy with a 15 hp Yamaha 2 stroke. . No issue planning with 4 adults.
MY engine weighs 79 lbs. So I believe the 109 lbs for the 25 hp.
2 stroke vs 4 stroke.....A friend with the same dinghy and a 15 hp 4 stroke Merc raced one day. We were 100% neck and neck. 2 stroke did not plane faster. I actually started to edge away by a foot or so when we ran out of room in the river after a minute or so.
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Old 05-31-2018, 10:24 AM   #12
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That’s easy,
Two stroke.

But I don’t think they developed four stroke outboards for emissions. The first 4s I remember was an OB called Lawson. Four hp as I recall but there may have been others.

The first large 4s OB was the 55hp Homelite. And I think it was to appeal to folks that were alergec to smoke and mixing. And of course everybody likes the much smoother idle. But smoother above idle is a tossup IMO. And then there’s noise. At an idle the 4s is king as it is w smooth running. But who runs a marine engine at an idle? Most all get worked hard and while working a 2s is king at mid throttle (the usual) as twice as many power strokes is an advantage. A small 2s OB at mid-low power is sweet indeed.

But since emissions came along the big difference is weight.
The heaviest thing in an engine is the crankshaft. Many car engines suffer a bit from excessively light crankshafts and I’ll bet 4s OB’s do to.
Motorcycle Grand Prix racing saw only one 4s contender for many decades (Honda) and weight I’m sure an issue but I think it was more a matter of power. Nothing could match a screaming two stroke. Honda was determined to win though and went to extreme measures. One I recall was elliptical cylinders. One can easily imagine some really big valves. Can you imagine building it? But none of it ever produced a win for Honda.

The combination of a sweet mid-range and light weight makes the 2s irresistible to me. But I have one 4s .. 60hp. I bought it new and mostly for less fuel consumption. But for small OB’s it’s 2s all the way for me.
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Old 05-31-2018, 10:25 AM   #13
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That's way too much money for an '07 by the way.
I think they are pricing it to reflect that you can no longer get these and they are highly desired....or at least highly desired by people other than on this website...hahaha!!!!
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Old 05-31-2018, 10:38 AM   #14
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I honestly think that a 25 HP 2-stroke and a 20 HP 4 stroke are two completely different animals. The power to weight ratio is going to have a large influence on performance. If it were aq 25 hp 4stroke and a 20 hp 2 stroke, that might be a bit more inline.

I prefer being able to use straight pump gas and not having to premix, run rich, smoke, smell or run out of oil.
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Old 05-31-2018, 10:50 AM   #15
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"I think they are pricing it to reflect that you can no longer get these and they are highly desired....or at least highly desired by people other than on this website...hahaha!!!! "

Yes - exactly around here anyway.
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Old 05-31-2018, 10:57 AM   #16
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I have that dinghy with a 15 hp Yamaha 2 stroke. . No issue planning with 4 adults.
MY engine weighs 79 lbs. So I believe the 109 lbs for the 25 hp.
2 stroke vs 4 stroke.....A friend with the same dinghy and a 15 hp 4 stroke Merc raced one day. We were 100% neck and neck. 2 stroke did not plane faster. I actually started to edge away by a foot or so when we ran out of room in the river after a minute or so.
My answer was to the OP's question and not to your parameters.
But .. with your exact dinghies and the results you have seen I would suggest it was due to other factors other then the engines types.

Props, trim, drive ratio, weight, engine tune, weight distribution will all play a large role is such a small RIB - anything other then the engines itself is likely a large contributor.
Our boating group (large headcount) has/had many RIBS with varied hp over the years and the differences in the engines are pretty well set.

PS -your adults may be much lighter than what we see as the group of RIBS at about 10.5 feet struggle to plane with 20-25 hp. They get there but it takes a bit and may require tabs, etc.
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Old 05-31-2018, 12:19 PM   #17
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Need to double check the weights. 25 Yami is NOT 60lb, but I also doubt it is heavier than the 20 Tohatsu.

I'd shop for a 15 Yami two stroke. Little critter with way plenty power for a dink. Over that in hp and it's overkill.
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Old 05-31-2018, 12:27 PM   #18
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PS -your adults may be much lighter than what we see as the group of RIBS at about 10.5 feet struggle to plane with 20-25 hp. They get there but it takes a bit and may require tabs, etc.
No OUR adults are NOT lighter. Wish we were LOL. The 15 pops us right up. And that's sporting a full 6 gallon tank and a locker full of gear.
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Old 05-31-2018, 01:50 PM   #19
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I raced with a buddy in identical ribs. The dinghy I was in had an 8HP 2 stroke Johnson (it might have even been a 7hp). My buddy had a 9.9 Merc 4 stroke.

Off the line the 2 stroke was on plane and clearly had the hole-shot. I was able to very quickly pull away. Within minutes I had the 4 stroke merc by a HUGE lead (50+ boat lengths). So much so, I dind't bother looking back again. The race was about 1-1.5 miles (We were travelling from point A to Point B and decided to race for fun). About half-way there, the 4stroke merc passed me. I eventually lost sight of him.

The two-stroke definitely had the hole-shot and over short distances was a sprinter. The top end on the 4stroke was much higher and over time and distance crushed the 2 stroke.

I do think there are variables at play. However, not enough to change such a lopsided outcome.
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Old 05-31-2018, 02:22 PM   #20
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Most of you are comparing Apples to oranges. I bet not a one of you know what props were on which engine. Is the 2007 carburated or fuel injected. Do you need low end torque or do you need economy. Do you need the lightest engine for lifting or do you want quiet. These are the more important questions.
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