Are 4 strokes starting to win ?

[Landlockedpirate]

I admit it, i love 2 strokes. They are simple and light and I really think they compliment small ribs and sibs better than a 4 stroke.

But then a question by a newbie made me look at the tech specs for the new small Selva outboards.

The 9.9 4 stroke weighs just 30kg, which is 6kg lighter than the Yamaha 2 stroke and only 4kg heavier than the class leading Tohatsu 9.8 2 stroke.

So have small strokes turned a corner, will we see the 15hp start to come down from the 40kg range in the near future ?

[Nick Hearne]

Originally Posted by Landlockedpirate

The 9.9 4 stroke weighs just 30kg, which is 6kg lighter than the Yamaha 2 stroke and only 4kg heavier than the class leading Tohatsu 9.8 2 stroke.

Yes but for that extra 6kg you can have a 15hp 2 st yam (36kg)
No point comparing with the smaller HP from the same block!

[henryfreston]

And it's not all about weight.

2 stroke produce a power stroke twice as often so have better holeshot.

[chris.moody]

My Honda bf50 has an equally impressive holeshot as my previous Yamaha 40 Autolube. I think there are pros and cons for both 2 stroke and 4 stroke. For some 2 stroke is the better option, but I'm happy with my 4 stroke on a 4 metre rib.

[chris.moody]

On Sunday I took off from a standing start alongside "zestorer". A Honda BF50 4s against a Tohatsu 50 2s, on two identical ribs (SR4's). Zestorer was 2 up, I was single handed (but I'm fatter that the occupants of Zestorer). Both ribs seemed roughly equal on acceleration. So yes the 2 stoke would have won if it had been single handed but the difference is marginal (unless James wasn't really trying, which could be true).

[matt h]

my 2004 40 yam four stroke outran a mid 90s Mariner 40 two stroke (just) SR4 on acceleration and top speed in my SR4.

[Landlockedpirate]

Originally Posted by Nick Hearne

Yes but for that extra 6kg you can have a 15hp 2 st yam (36kg)
No point comparing with the smaller HP from the same block!

Yep, its a fair point. But the 15hp, 4 stroke Yamaha is now just 39kg, down over 12kg on its lardyarse previous version.
So they are getting a lot closer.

[Peter_C]

4 Stroke all the way! Environmental reasons should be the number 1 reason for them. I feel guilty every time I start my 2 stroke up and see a sheen of oil on the water.

I was reading another thread where the guy has to have a 4 stroke in order to run it on local lakes in Portugal. Some of our cleanest lakes here in the USA have banned 2 strokes also. It is a trend that will continue.

Of course the direct injection 2 strokes are completely different, but even they barely meet the emission standards put forth today.

[Landlockedpirate]

Originally Posted by Peter_C

4 Stroke all the way! Environmental reasons should be the number 1 reason for them. I feel guilty every time I start my 2 stroke up and see a sheen of oil on the water.

.

But if thats your logic, surely your boat should have a stick, scraps of string and flappy bits instead ?

[Wibs]

I've just gone the other way.....

I had a 2003 Suzuki DF50 on a 4.5m Avon Adventure, I now have a 2003 Tohatsu M50D2 on a SR4

Both in approx same condition and hours.

Suzuki was quiet, smooth and very economical. It loved doing 2k revs and pootle up rivers at 6knts comfortably. The hole shot was more of a relaxed affair, and at WoT I'd hit about 28kts

The Tohatsu delivers it's power completely differently, it's instant but very on or off...! It hates doing anything under 3k, and is slightly less economical than the Suzuki......but it puts a grin on my face that the Suzuki didn't..!!! It also hit 34knts with two up on Sun, without really pushing the hull.

Nothing we all didn't know really.?

However....I did have go on Tigga, and was quite surprised with the holeshot.

Would I swop..........hummmm...........nah. but on a bigger boat I'd prob want to go 4st.

[Poly]

Originally Posted by Peter_C

4 Stroke all the way! Environmental reasons should be the number 1 reason for them. I feel guilty every time I start my 2 stroke up and see a sheen of oil on the water.

In the small portable market where they tend to be laid on there side by mistake every so often I'm not sure a 4 stroke is actually better for the environment - have you seen the smoke etc when oil goes places it shouldn't!

Originally Posted by Landlockedpirate

But if thats your logic, surely your boat should have a stick, scraps of string and flappy bits instead ?

I don't think it follows that being concerned about needless pollution = avoiding internal combustion engines all together.

[matt h]

Originally Posted by Wibs

I've just gone the other way.....

I had a 2003 Suzuki DF50 on a 4.5m Avon Adventure, I now have a 2003 Tohatsu M50D2 on a SR4

Both in approx same condition and hours.

Suzuki was quiet, smooth and very economical. It loved doing 2k revs and pootle up rivers at 6knts comfortably. The hole shot was more of a relaxed affair, and at WoT I'd hit about 28kts

The Tohatsu delivers it's power completely differently, it's instant but very on or off...! It hates doing anything under 3k, and is slightly less economical than the Suzuki......but it puts a grin on my face that the Suzuki didn't..!!! It also hit 34knts with two up on Sun, without really pushing the hull.

Nothing we all didn't know really.?

However....I did have go on Tigga, and was quite surprised with the holeshot.

Would I swop..........hummmm...........nah. but on a bigger boat I'd prob want to go 4st.

The suzi 50 only pushed out 42 at the prop but the twatsoo does 50hp so you will feel the difference. put a 2014 suzi on it and it will now give it a run for its money i would guess.
Around the IOW at the weekend, (67miles) in my SR4.7 with yam 60 it burnt 72 litres mostly flat out.with a 13x19 pitch proP.
the Ribcraft 4.8 with A 60 efi i used Only 33 litres with a 13 pitch which was under propped. Have ordered a 14 pitch 4 bladed alloy for next run out.. Very substantial fuel saving.

[Rogue Wave]

Originally Posted by Peter_C

I feel guilty every time I start my 2 stroke up and see a sheen of oil on the water.

.

great smell though. I think any powerboater that says they care about the environment so they use a fuel efficient engine is deluding someone, probably themselves, but not me. I guess my definition of a powerboater is someone who burns fuel for fun on the water, or in the case of the Whisperers for Charity and fun. I'm honest enough to say I get my fun from burning fuel, and accordingly I can't genuinely care about the environment because I'm doing my bit to destroy it. If I did care then I wouldn't go powerboating and that ain't gonna happen.

I love 2 strokes and I could cut my tounge out for what I am about to say but yep I think 4 strokes are getting there. We have a Yammie F70 which is only 10% heavier than our 2 stroke Yammie 70 and easily has the same power and torque. In addition to that it uses about a third of the fuel, which makes me very happy as it cost me me so much less to run the boat Oh yeah and it's good for the environment!

There is a fella on the Macmillan cruise thread claiming he got round the IOW (60 Miles)in a 5.5 metre boat and only used 30 litres and I certainly believe him. that's .5 of litre per mile

So Unlike our 'enry I think weight is crucial, and when the weight is comparable to a similar powered 2 stroke then Electronic ignition and higher rrevving is going to contribute a lot toward producing from a 4 stroke the extra torque and holeshot that you experience from a 2 stroke's extra banging

Having said all those lovely things it would take a very special engine to get my Yammie 90 2 stroke of the back of my Avon 5.4 Ah the smell, the noise and the grunt and that's just me!

[Bigtalljv]

Why is hole shot so important? It's always the first thing 2 strokes are said to be superior in. when I go in my boat it's usually to go somewhere. the hole shot is 8 seconds of a day trip. Why do I care if it's 8 seconds or 12?

I'm running a 250hp 4-stroke so maybe this is a portable engine conversation?

jason

[Poly]

Originally Posted by Bigtalljv

Why is hole shot so important? It's always the first thing 2 strokes are said to be superior in. when I go in my boat it's usually to go somewhere. the hole shot is 8 seconds of a day trip. Why do I care if it's 8 seconds or 12?

I'm running a 250hp 4-stroke so maybe this is a portable engine conversation?

jason

Are you the type of boater who gets on board, sets the throttle (usually to full) and then sits back for several hours? Either you only go in flat calm conditions or would find working the throttle more comfortable - in which case acceleration is nice to have.

[jyasaki]

Originally Posted by Poly

Are you the type of boater who gets on board, sets the throttle (usually to full) and then sits back for several hours? Either you only go in flat calm conditions or would find working the throttle more comfortable - in which case acceleration is nice to have.

JV's on the west coast of California; I can pretty much guarantee he's not going to get a lot flat calm days.

But your response doesn't really address his statement (or question or whatever it was): Hole shot performance is nice to have, but it only applies to the times you are starting off after dropping off plane. As he said, that is generally a very small percentage of the time on the water.

jky

[Landlockedpirate]

Originally Posted by Rogue Wave

great smell though. I think any powerboater that says they care about the environment so they use a fuel efficient engine is deluding someone, probably themselves, but not me. I guess my definition of a powerboater is someone who burns fuel for fun on the water, or in the case of the Whisperers for Charity and fun. I'm honest enough to say I get my fun from burning fuel, and accordingly I can't genuinely care about the environment because I'm doing my bit to destroy it. If I did care then I wouldn't go powerboating and that ain't gonna happen.

I love 2 strokes and I could cut my tounge out for what I am about to say but yep I think 4 strokes are getting there. We have a Yammie F70 which is only 10% heavier than our 2 stroke Yammie 70 and easily has the same power and torque. In addition to that it uses about a third of the fuel, which makes me very happy as it cost me me so much less to run the boat Oh yeah and it's good for the environment!

There is a fella on the Macmillan cruise thread claiming he got round the IOW (60 Miles)in a 5.5 metre boat and only used 30 litres and I certainly believe him. that's .5 of litre per mile

So Unlike our 'enry I think weight is crucial, and when the weight is comparable to a similar powered 2 stroke then Electronic ignition and higher rrevving is going to contribute a lot toward producing from a 4 stroke the extra torque and holeshot that you experience from a 2 stroke's extra banging

Having said all those lovely things it would take a very special engine to get my Yammie 90 2 stroke of the back of my Avon 5.4 Ah the smell, the noise and the grunt and that's just me!

I know exactly what you mean about the Yam 90, dad had one on the family ski boat as a kid, awsome piece of kit.

But I think you understand what I am trying to say, 1 of the big negative factors of 4 strokes is weight, and thats starting to come down. (the Yam F70 is our shortlist of 2 to replace dads ageing Honda 50 on his sailing boat).

Personally I'm still sticking with my collection of transportable 2 strokes for now.

[henryfreston]

Originally Posted by matt h

The suzi 50 only pushed out 42 at the prop but the twatsoo does 50hp so you will feel the difference. put a 2014 suzi on it and it will now give it a run for its money i would guess.
Around the IOW at the weekend, (67miles) in my SR4.7 with yam 60 it burnt 72 litres mostly flat out.with a 13x19 pitch proP.
the Ribcraft 4.8 with A 60 efi i used Only 33 litres with a 13 pitch which was under propped. Have ordered a 14 pitch 4 bladed alloy for next run out.. Very substantial fuel saving.

I burnt roughly 28-29 liters on round IoW with my 2 stroke (granted it is DI though!)

[Maximus]

Hole Shot is not only nice to have...but positively essential in the Rough Stuff!
My 250 DF Suzuki delivers Great Hole shot,is Whisper quiet, Clean running and Cruising returns about the same fuel economy as the 130 etec!!!...and no oil to worry about Love it.
I would say that the smaller the RIB,the more important the weight consideration.
Also the importance of the right Prop for the type of Boat....and Boating you do is not to be underestimated.

[Max...]

Originally Posted by Bigtalljv

Why is hole shot so important? It's always the first thing 2 strokes are said to be superior in. when I go in my boat it's usually to go somewhere. the hole shot is 8 seconds of a day trip. Why do I care if it's 8 seconds or 12?

I'm running a 250hp 4-stroke so maybe this is a portable engine conversation?

jason

Blimey, running a SIB with a 15 2 smoke on and off the beach and along the coast in typical UK conditions the hole shot on and off is a heck of a lot more than 8 seconds in a day, more like 50%!!