Time for bigger engine?

[zipper]

Hey, we are all suffering from severe cabin fever across the land... hence sick humor!

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Tell me about it...It's been a long, on the hard, Winter. When it warms up, we will be able to start the long list of boat mods.

 

[yamadabbadoo]

I doubt they ever will, or could... It's a different beast, way more refined, quiet, efficient (and... expensive to make!) - as compared to the little brutes of 1.8s.

I often wonder about it. But these jet boats of ours have intrinsic limitations that may curtail the power/fuel efficiency equations. For example, you just can't use any of the stepped hull designs to increase efficiency (reduce drag and friction on plane) because of the water intakes, etc.

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This is the info I was looking for. I am a bean counter so I dont know about boat designs and such. I started boating late in life, I hope I have time to learn all this...

 

[yamadabbadoo]

I agree, and was wondering what percentage of Yamaha’s revenue comes from boats vs jet skis.

Maybe Yamaha should have ditched the pass-through stern and gone with 3 N/A 1.8’s...

I have wondered if 3 1.8 engines would be possible. I imagine that would make for a fun 0-30...

 

[the MfM]

Great, thanks for answering my question. Forums are awesome. Cannot believe I waited all these years to join.

Just give it time. New engines are in the works...

|boating insight|-manufacturing-development-and-design-evolves|ENGINE/jet||

 

[yamadabbadoo]

Just give it time. New engines are in the works...

|boating insight|-manufacturing-development-and-design-evolves|ENGINE/jet||

Turbo in the works? I doubt that. Yamaha doesnt do Turbo...

 

[Jgorm]

The more relevant question is who needs a 27' jet boat with jet ski engines? Doesn't make sense. Put in a mercrusier 7.4 and a bravo2 io. Or twin 350s. It would be faster and more efficient. A 27' boat is too big to use in water shallow enough to justify a jet.

 

[JBehrens]

The more relevant question is who needs a 27' jet boat with jet ski engines? Doesn't make sense. Put in a mercrusier 7.4 and a bravo2 io. Or twin 350s. It would be faster and more efficient. A 27' boat is too big to use in water shallow enough to justify a jet.

Putting an off the self engine and driveline would not be the style of Yamaha. They like that everything is jet based and the same (at least for the U.S. market).

 

[swatski]

Maybe Yamaha should have ditched the pass-through stern and gone with 3 N/A 1.8’s...

Apparently they considered it but I guess went the other way.

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[Bluewater272]

The more relevant question is who needs a 27' jet boat with jet ski engines? Doesn't make sense. Put in a mercrusier 7.4 and a bravo2 io. Or twin 350s. It would be faster and more efficient. A 27' boat is too big to use in water shallow enough to justify a jet.

The only reason to buy the Yamaha 275 is because you want a jetboat. If you're going to buy an I/O, there are a dozen other (arguably better) options to choose from.

 

[JBehrens]

The only reason to buy the Yamaha 275 is because you want a jetboat. If you're going to buy an I/O, there are a dozen other (arguably better) options to choose from.

Agreed, for the money and size, something from the Monterey line is likely to be more appealing then the 275. Even the M6, slightly smaller but still keeps water sports as a priority, is a better option then the 275 IMO.

 

[swatski]

The only reason to buy the Yamaha 275 is because you want a jetboat. If you're going to buy an I/O, there are a dozen other (arguably better) options to choose from.

I know, and there are various reasons for choosing/wanting a jet boat but the two major ones are water sports safety (no exposed prop), and shallow water boating.
The 275 is obviously not meant/equipped for watersports... so it must be the shallow water!


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[haknslash]

In my recent boat shopping, draft specs was something I was looking into (and concerned with) for my next boat. What I found was that surprisingly the draft on jetboats, especially larger ones, is not much less than non-jet watersport boats. I would have thought the difference was much great but it's not. Take the 275 has a draft of 22" yet remember it shouldn't be operated in less than 3' (36") of water because of the intakes sucking up stuff. The draft on my Moomba Max is 28". There are times when I've had to boat in just over 2' of water near a dock or in a narrow slough with my AR192 which has a draft of 15". Obviously I won't be exploring tight and narrow sloughs in my new boat lol but when I started looking at the specs really closely on these boats and when you factor in they say they shouldn't be operated in less than 3' of water, having rudders and ride plates hanging below the hull, the shallow draft "advantage" of a jet draft is mainly in the event you're beaching it or anchored just offshore.

An outboard or stern drive is a completely different animal though and adds 15-20" to the draft to a boat. However it can lift the drive out of the water allowing you to beach it in very shallow water just like a jet drive. Take the Cobalt R7 for example. It has a draft of 37" with the drive down but only 21" with it up. That's pretty impressive for such a large runabout.

That being said, you can't do this stupid stuff in a prop boat lol. I felt bad for that WaveRaider

 

[Ancient canoe]

It will be interesting to see the test numbers come out on the 275 with twin SVHOs. In the boating magazine promo video one fuel data point flashed and it was atrocious. If that's the case, I don't think those will be viable boat engines. It will also be interesting what the new BRP engine does in boats as well. Are those on the market yet? I know those are going to offer a level of performance for Scarabs and Chaps that Yamaha can't match right now.

 

[Jgorm]

The only reason to buy the Yamaha 275 is because you want a jetboat. If you're going to buy an I/O, there are a dozen other (arguably better) options to choose from.

Right but what logical person thinks "i want a 27' jetboat". Probably the same guy that had a 27' airboat and a 27' dinghy.

 

[JBehrens]

It will be interesting to see the test numbers come out on the 275 with twin SVHOs. In the boating magazine promo video one fuel data point flashed and it was atrocious. If that's the case, I don't think those will be viable boat engines. It will also be interesting what the new BRP engine does in boats as well. Are those on the market yet? I know those are going to offer a level of performance for Scarabs and Chaps that Yamaha can't match right now.

Some quick napkin math based on the AR195's numbers would give each SVHO burning 20.5GPH at wide open for 41GPH total. So ~2.2hours of fuel, I would hope it hits 50mph so that would give you ~110 miles of range. Almost equivalent to the on paper numbers of a twin 1.8 boat. Say it gets 25GPH at best cruise, that's still only 3.6hours of fuel for ~130 miles of range (if at 35MPH).

The SVHO is a good wave runner engine but in a boat it drinks.

 

[haknslash]

Some quick napkin math based on the AR195's numbers would give each SVHO burning 20.5GPH at wide open for 41GPH total. So ~2.2hours of fuel, I would hope it hits 50mph so that would give you ~110 miles of range. Almost equivalent to the on paper numbers of a twin 1.8 boat. Say it gets 25GPH at best cruise, that's still only 3.6hours of fuel for ~130 miles of range (if at 35MPH).

The SVHO is a good wave runner engine but in a boat it drinks.

How does that give you 110 miles? If it drinks twice as much fuel as a twin 1.8 naturally aspirated but has twice the fuel capacity it should equal out to being near the same range. Last year or maybe it was the year before there were several 24’ Yamahas that ran out of gas to Bimini (approx 50 nautical miles). Range is going to depend entirely on conditions. Looks like the 275 will be carrying extra fuel so factor that in as well to more weight and more fuel burn. Going to be twice the cost to refuel as often as a 24’ boat...YIKES!!

 

[JBehrens]

How does that give you 110 miles? If it drinks twice as much fuel as a twin 1.8 naturally aspirated but has twice the fuel capacity it should equal out to being near the same range. Last year or maybe it was the year before there were several 24’ Yamahas that ran out of gas to Bimini (approx 50 nautical miles). Range is going to depend entirely on conditions. Looks like the 275 will be carrying extra fuel so factor that in as well to more weight and more fuel burn. Going to be twice the cost to refuel as often as a 24’ boat...YIKES!!

I did 2.2 hours of fuel at WOT with say 50mph top speed (that is assuming best conditions and a top speed of 50mph) for 110miles. (2.2x50=110). The 275 is only 90gal so not quite double the capacity of the 242's.

Regardless, I would not want to be filling that tank. Just 2 fillups would completely drain the 180gal houseboat toy tank, leaving the need for a fuel dock trip.

 

[biffdotorg]

Turbo in the works? I doubt that. Yamaha doesnt do Turbo...

OMG, that was a stealthy rick-roll. I never saw it coming.

PS: Yamaha does do turbo, and very well mind you. The sidewinder at under 1ltr putting out a very stable 208hp is a rocket on the snow!

My opinion, Yamaha is sticking to those PWC engines as it is their special sauce allowing them layouts that cannot be done with traditional engines. Stand next to one of those Yamaha outboards and note the size of the powerhead. OMG, they are massive. Cost/size will keep them using PWC engines.

But the point is made, on these larger boats, they have to consider their competition more. And I truly believe, that is why these 275 series boats are pre-order only. They are feeling out the market before mass producing. They want to know if folks will give up performance/economy/noise for that unique layout.

 

[swatski]

My opinion, Yamaha is sticking to those PWC engines as it is their special sauce allowing them layouts that cannot be done with traditional engines. Stand next to one of those Yamaha outboards and not the size of the powerhead. OMG, they are massive. Cost/size will keep them using PWC engines.

That is exactly right, the transferability of those drivetrain/engine platforms between their jet skis and boats has given them tremendous advantages, as they use skis as testing ground. The problem is it only works that far.

The important issue to remember is the suitability of those engines to run the pumps of the size that they use, again going from jet skis to boats. Generating trust with these small diameter impeller pumps requires high rpm, given direct drives. It’s just one constrain on top of another, at the end.

I really don’t see how this 27 foot concept would take off. I kind of like the lines and the general styling, but the rest of it like fuel inefficiency and noise is making those look almost silly, next to their new competition it the 130k segment.

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[AboveTheBest]

That poor WaveRaider