Are 1.8s ( 360 HP ) really enough power ?

[Evil Sports]

With fuel prices rising to no one knows where, last thing I want is a bigger thirstier set of twins in my boat. Going 50 is fun for about 4 minutes then its just a waste

 

[2kwik4u]

Lots of interesting comments here. Lots of great ideas, and good market analysis in general.

There is, by and large, some engineering limitations to "just putting a larger motor and pump in there"......By and large axial flow centrifugal pumps (what our jet pumps are) like higher revs. THe MR-1's went to 10k, the new 1.8's go to 8k-ish. You're not going to find a pump that likes much below ~4-5k as a "cruise operating" condition. They are aren't very efficient at lower revs, and take more power to produce the same pressure differential.

Here's a compressor map from an axial flow centrifugal pump. Vertical axis pressure ratio. This is the ratio of low to high side pressure. We've seen pressures of 30psig on the cooling system so we're talking around a 2.0 or so pressure ratio for our boats at full revs. Horizontal axis is mass flow rate. This is the VOLUME of water that it's moving. A larger pump will move more water, but still only generate similar pressure levels. The colored islands are efficiency zones. This is the ratio of work input to work output. Some work is lost to heat; more efficient is better. Finally, the curved lines over the colored area are pump shaft speeds. As you add speed to the input shaft it moves more water, at higher pressures.


(click for larger image)

So what you'll find is that as you go UP in pump size, you require much more torque to maintain that same shaft speed. More torque is the root problem here. To get more torque you need a larger Mean effective pressure in the engine. Two ways to get that. Increase piston size/compression ratio, or add boost. Adding to engine size will, in general, LOWER max RPM due to piston speeds, valvetrain speeds, column loading in connecting rods, and a whole slew of other reasons. Well, we WANT those revs. We NEED those revs for the pump to continue to operate efficiently. You can see this in work in I/O as well. Look at the outdrive ratio, it's typically between a 2.0:1 and a 1.4:1 or so. These are OVERDRIVE ratios. They're geared UP, not down. The little 3.0L 4cyls have like a 1.4-1.5:1 because torque is limited. This limits prop speed, and overall speed. Check a large 7.4L and they'll have like a 2.0-2.2:1 ratio. Plenty of torque, but no revs so they need to spin the prop faster. Keep in mind props are also axial flow "pumps"; they just use "traction" with the water instead of a pressure differential and a nozzle to deliver thrust.

SO........that is a ridiculously summarized set of reasons why large displacement engines will most likely NOT be coming to recreational jet propulsion systems. The small engine, axial flow pump, and jet nozzle pairing is well suited to smaller, higher revving engines. I would guess something along the lines of a turbo 2.0L (lots of magical engineering things happen at a 0.5L per cylinder size, but that's for another day) with a 170 or 180mm pump is about as big as we'll ever need. We're already pushing 25ft boats into the 50mph range on stock supercharged 1.8L's. Imagine a 212S with twin turbocharged engines, and 170mm pumps......I bet that's a 65+mph boat right there. At those speeds we're, IMO, starting to look at some safety issues with recreational bowriders, as the dynamics of wetted surface, hull strength, and things like "chine walk" start appearing.

All boils down to cost, market demand, and intended consumer. Most people are REALLY happy with a 50mph 24ft boat that costs $60k or less.

TO answer the initial question......yes, twin 1.8's are plenty for this segment IMO.

 

[Bluewater272]

For the intended use of our style boat, the 1.8s are entirely adequate. Gets out of the hole fast, will run at 50MPH (little faster if the tides and winds are right), but most of us probably spend 95% of time at around 30MPH cruising for economy. I drool over some of these boats with twin and triple outboards, but those boats are also significantly larger and heavier than ours, necessitating that increase in power. My next boat will be something with twin outboards, but like others mentioned, they are stupid expensive. A pair of 350/400s rigged and installed costs more than most yamaha boats.

 

[HangOutdoors]

I think it is more about pushing more weight and people whom load their boats with 7-10 passengers consistently. Right now they have 6 models in the 21' and the big defining factor from the AR210 to the 212 and above are the larger engines. If/When they start building 22' models, The 3 cyl. TR-1's would be inadequate in their current form. You would have a sub 40 boat with nothing in it and a couple of people. Whether or not they put the 1.8's in all of the 22' footers will be interesting, or perhaps they lose a trim level or two and adjust the pricing, will be interesting.

 

[anmut]

I think it is more about pushing more weight and people whom load their boats with 7-10 passengers consistently. Right now they have 6 models in the 21' and the big defining factor from the AR210 to the 212 and above are the larger engines. If/When they start building 22' models, The 3 cyl. TR-1's would be inadequate in their current form. You would have a sub 40 boat with nothing in it and a couple of people. Whether or not they put the 1.8's in all of the 22' footers will be interesting, or perhaps they lose a trim level or two and adjust the pricing, will be interesting.

I agree - in fact Yamaha should install the 1.8s into any 21+ boat as standard, and use the SC versions as the upgrades.

 

[the MfM]

Just saying...

 

[David Martin]

360hp twin 1.8 is plenty for my SX240ho I it all about HP to weight raito. My last boat a Crownline 21ft cabin cuddy was a little heaver than the Yamaha it ran 52mph on a 340HP engine I buil.........t through an Alpha one gen 2. Computer says 54.8 on the Yamaha did not use gps that day.

Big difference between the 2 boats, the Yamaha comes out of the hole like a scalded ape.

 

[SCSCOTT]

Isn’t 180 hp what the NA (non CA) 1.8s put out and the SC 1.8s put out 220hp to 240hp? If so at least a few of the new models (270 and 252) put out 440hp to 480hp, correct?

I was wondering about this too. I found a Yamaha WaterCraft announcement from August 2020 stating "the 255 FSH Sport E gets twin 1.8L supercharged Yamaha SVHO® marine engines for a combined 500-horsepower". Aug 2020 product announcement

So from that can I assume all 1.8L SVHO engines in all boats are 250HP? Or is that only in the larger Twin 1.8L boats for 500HP total? Geico/BoutUS insurance considers my FSH 195 250HP. However I can not find official Yamaha information or news release that states this.

I can find info on the Skis from various sources and this article from 2019 on the AR195 from Boat Mag stating 250HP. Boat Mag AR195

So from all that I would assume all 1.8L SVHO engines are 250HP or are there detuned variants? But you all know what happens when you assume.

 

[Ronnie]

Yamaha Has not posted their engines power specs in HP for many years. They describe power output of their engines via kilowatt hours and many use a formula to determine how much horse power this equates to. Others Dyno test their machines somehow to determine HP. When using the formula the hp of a sc 1.8 does not equate to 250.

side note: Another thing to consider is that CA versions of the 1.8 engine have catalytic converters so these engines produce less KW/HP. There is no price break for boats with the CA motors, effectively customers are paying the same price for less HP.

 

[SCSCOTT]

Yamaha Has not posted their engines power specs in HP for many years. They describe power output of their engines via kilowatt hours and many use a formula to determine how much horse power this equates to. Others Dyno test their machines somehow to determine HP. When using the formula the hp of a sc 1.8 does not equate to 250.

side note: Another thing to consider is that CA versions of the 1.8 engine have catalytic converters so these engines produce less KW/HP. There is no price break for boats with the CA motors, effectively customers are paying the same price for less HP.

Here is a link from 2014 for the 1.8L SVHO California EPA certification and the 184 kw translates to 246.75 HP. Granted this is for a Ski. If this number still stands today. They are not getting much less HP in CA. I have no proof just conjecture... CEPA 2014 Some converters say 250 HP from 184 kw.

250 Conversion

I have also seen Yamaha underrates the engines and there is a sticker somewhere on the engine it's self with a kw number on it. I will have to look.

Would be nice if they would just publish this info. We are left to be detectives.....

 

[biffdotorg]

I think this last post defines the issue. As most of us agree that the speed and performance is quite adequate, but more are worrying about the number on the tag.

I asked a guy on Facebook the other night if someone had put a pair of AR192 engines (220hp 1.8 SC) in his 242 limited. As he had a big 440x sticker on the side of his 242. He said no, this was a special model from yamaha with a pair of 220hp engines. Although he was actually posting that he was disappointed that his performance had dropped from 50mph to 46mph. (the same as a stock 242. So obviously the guy that sold it to him, was getting some value out of his wife's vinyl cutting skills.

So if it makes anyone feel better, as it sure made him feel better, put a 440 or 500hp sticker on the side of your boat. Brag to your friends that you actually have 600hp. The fact of the matter is, a pair of 1.8's in a 242 or 250 series will still push 10 people around just fine. And there are very few places I care to drive this thing 50mph, let alone faster. The hull was just not designed for those speeds safely.

Wish all day long, but until they design a hull that can take 60+mph, or a pump that will not cavitate with more than 250hp, I don't need it. And "need" should never come into a guys conversation about HP. It doesn't with any other powersport product I own. And we shun those that utter the word.

 

[mraz72]

Outboard guys look at our boats as toys? LOL

you mean the outboard guy, in their toy, looks down on our toy LOL

guess what, who cares.

 

[biffdotorg]

Outboard guys look at our boats as toys? LOL

you mean the outboard guy, in their toy, looks down on our toy LOL

guess what, who cares.

I find in humorous that it takes so much more HP to push their boats up to nearly identical speeds. The kicker is, I am doing it with 6-8 people on board. The cost benefit of additional HP in boats, as described in a previous post in this thread, proves Yamaha has the formula figured out on powering these boats and not disappointing the masses.

 

[Babin Farms]

I

Well then, just try the shallow water challenge. Step 1, know the shallows. Water depth, bottom condition, logs etc. Step 2, get on plane and run thru 12" of water while the big mouth has to raise his OB or lower unit and walk it thru the shallows. Step 3, you arrive at the same marina as the big mouth 15 minutes before him, he docks and comes over to you and asks, "how did you do that"? My reply was, as I chuckled "It's a jetboat". His last comment "Wow, I did not know you could do that.

That is how it went leaving the Sandbar State Park in 2018. We went under the bridge in no wake speed, he was right behind me, but while I was still in the channel, I "hit it" and got up on plane before I got to the 12" deep water, I know this area and had just come thru the other way a couple of hours before. I skipped across the shallows at speed while he had to raise his lower unit and walk thru below knee deep water. I had the boat all put away and covered by the time he got back to the marina with his rooster tail between his legs.

This picture was taken in 2016 when it dried up. Two Pro Bass boats with big OB's, in a tournament, were pulled off this sandbar this past Saturday in 6" of water. You can give them all a black eye, just know what you are getting into and what your boat can do.

This is a bit too shallow to try, lol, I paddle boarded under the bridge with the Yamaha on the other side.

View attachment 156137

Had something similar happen in Bimini. Heading to a plane wreck I was cruising along about 30mph and 3 larger CC with twin outboards went racing by me but as we got closer and it got shallower I went right by them without hesitation as they were trimming up and got to the wreck quite a while before them.
With the fuel economy of my boat, HP and the way it all comes together I couldn't be more pleased with my mere 320hp.

 

[mraz72]

ease of maintenance, less stuff to break, great little family boat. There are a bunch of yamahas at my marina (yamaha dealer next door), I've seen the same folks for years, not many issues with these boats.

 

[Adrian @ JB Solutions]

Outboard guys look at our boats as toys? LOL

you mean the outboard guy, in their toy, looks down on our toy LOL

guess what, who cares.

I've yet to come across someone that thinks this way. Most are pretty interested in the boat and give compliments. I'm sure they are out there, but probably the guys with 300k worth of engines alone.... they probably look down on all other boats lol.

I went out with a buddy on Sunday who rides in a lot of boats, mostly spearfishing 100-200 miles off the coast. He was super impressed with the acceleration and how the boat ran.

 

[anmut]

As long as we can keep the 1.8 NAs in the future I'll be a Yamaha customer. I love feeding it just 87 octane...

 

[mraz72]

I don't look down on other boats, so that's why I don't get the thinking. I enjoy looking at all of the different boats out there, much more varied than cars.
However you get out there, you're a boater, enjoy the water.

before I could afford a 24', I used to get out on the water in a canoe, than a kayak, than I had a Hobie Tandem Island for a few years (loved it), now I'm in a powerboat

 

[Adrian @ JB Solutions]

I don't look down on other boats, so that's why I don't get the thinking. I enjoy looking at all of the different boats out there, much more varied than cars.
However you get out there, you're a boater, enjoy the water.

I have a friend with 12' catamaran and I think its the coolest thing ever lol.

 

[2kwik4u]

As long as we can keep the 1.8 NAs in the future I'll be a Yamaha customer. I love feeding it just 87 octane...

As much as I think a twin supercharged 212 would be amazing (Bring back the SS nameplate?!?!), I'm not sure I would own one. I purposely bought the 190 over the 195 sitting next to it, and fuel usage was one of the main reasons (color and cost were the other two major ones).

The N/A 1.8's are just so simple and reliable, they're really hard to beat.