Scarab 255 vs. Yamaha 242 LS

[haknslash]

The BRP motors are closed loop. The motors use coolant/antifreeze just like your car or truck does. The ride plate is a heat exchanger (think radiator) of the cooling system. Hot antifreeze enters the ride plate where it gets circulated to exit as cool antifreeze that is pumped into the motor.

The exhaust manifold and muffler being water cooled is not as big of a deal to me unlike the engine. As much as a like Yamaha, I appreciate a closed loop system. I wished they offered it in the future.

Here's a diagram I found that helps illustrate their cooling system...

 

[subysti]

Closed loop except for the exhausts

 

[haknslash]

Closed loop except for the exhausts

Yes but the exhaust isn't the motor

 

[morgro269]

Exhaust circulates external water. Kind of makes the closed loop engine a moot point.

 

[MikeyL]

Maybe this will answer the question factually:

Closed Loop
Closed-loop cooling system (Sea Doo ONLY) works much the same as an open loop system but instead of having water flow into the engine to cool it, antifreeze is used instead. The antifreeze is circulated through the engine than to a ride plate. The ride plate is just a heat exchanger or a radiator that converts the hot antifreeze into cool antifreeze.

The way the ride plate works is that it allows the antifreeze to circle around in the plate. While circling around, the antifreeze is being cooled by colder water touching the ride plate. The heat transfers from the antifreeze to the ride plate and is carried off to the water. Colder antifreeze is pumped back to the engine to cool it.

Now you might be thinking how reliable is this closed loop cooling system? It’s so reliable that all modern cars, planes, and even trains use it! Yes the car you drive into work uses the exact same system as a Sea Doo watercraft uses. So if your car uses it why wouldn’t your jet ski?

On top of all that since its a closed system you won’t take in any corrosive water. Since you don’t have anything eating away at the engine block of a Sea Doo you could have the engine last much longer.

Also since you don’t have water near the engine winterizing is even easier. No need to flush the engine on a Sea Doo since it is completely sealed up. But there is one drawback! The engine is completely sealed up but the exhaust and intercooler is still cooled by water and they will need to be flushed out for winter.

One big perk with the closed loop cooling system is that it can be controlled to keep the engine at a perfect temperature at all times. Where the open loop system can not. So if it’s extra hot that day the water will be extra warm too. Warmer water for an open loop system means the engine runs warmer which relates to you burning more gas and do more damage in the long run to the engine. Due to the nature of a closed loop system warmer days have no effect on the engine.

 

[subysti]

Closed / Half loop. I researched a LOT before I purchased. To me this is kinda like having 2 cooling systems.

 

[smashedheadcat]

I will comment about having a more constant operating temperature though. Both systems utilise a thermostat that can limit the amount of coolant (sea doo) or raw water (yamaha) that circulates through the engine. This thermostat will adjust it's flow to obtain and maintain a specific engine operating temperature. The temperature of the water you're boating in will always be cooler than the engine operating temperature so water flow will adjust accordingly in order to maintain a normal operating temperature. Both open and closed systems will maintain temperature in the same manner with no advantage to either.

At the end of the day, one engine circulates a fluid designed to promote engine cooling, prevent corrosion, is clean, and probably won't freeze during the winter.

The other engine circulates water with dirt, weeds, and salt depending on where you boat, and freezes overnight if the temp gets below 32 degrees.

Both systems get the job done, but pretending the yamaha variant is superior because you were "mislead".... really? Yamaha makes a nice boat, but unless you boat in a swimming pool full of filtered engine coolant, this advantageous for BRP.

 

[morgro269]

I'm not at all saying having closed loop cooling for only the engine is a bad thing at all. There's a lot of people out there that think the BRP engines don't use any raw water at all. The truth is they do. To me, that's half assed. Why not make it a true advantage and close the whole thing? The intakes can still get clogged and cause you to overheat. The cooling jackets can still have dirt/ pond scum/ salt build up and cause issues. Just something people should be aware of, that is all.

 

[smashedheadcat]

I'm not sure why they would leave the exhaust open, but if I had to guess, I'd say it allows the exhaust system to stay cooler at the tailpipe. In a closed system, you eventually have to scavenge the coolant back prior to the exhaust exit point whereas a an open can send the water wherever it wants, like out the tailpipe.

 

[haknslash]

I'm not at all saying having closed loop cooling for only the engine is a bad thing at all. There's a lot of people out there that think the BRP engines don't use any raw water at all. The truth is they do. To me, that's half assed. Why not make it a true advantage and close the whole thing? The intakes can still get clogged and cause you to overheat. The cooling jackets can still have dirt/ pond scum/ salt build up and cause issues. Just something people should be aware of, that is all.

I wouldn't really call it "half-assed". That just kind of sounds like you have an axe to grind with Seadoo or you think it's some marketing ploy and they are misleading people, which I don't feel they are.

There are a lot of prop boats out there that use water cooling for the exhaust and closed loop for the engine. Most I/O boats I remember were this way and if I recall most of the exhaust manifolds were made of cast iron which has good corrosion resistance. Remember seeing those boats with exhausts pouring water out? Yea that's water cooled. The rest of the exhaust was some grade of stainless steel. In the case of the BRP exhaust they say the use materials such as polymers (plastics), stainless and aluminum. All which have good corrosion resistance.

The only boats I can remember being air cooled are big commercial vessels and those use a fire retardant wrapping in the engine rooms. The reason you don't see this used on small boats is due to CG regulations plus there isn't enough open volume of cool air in such small engine bays to allow the heat to dissipate effectively. Raw water cooling is a very effective and free source of cooling for exhaust and nowhere near as vital as engine cooling.

 

[morgro269]

I get it... I just don't think it's fair to refer to the boat as being closed loop when only half of it is. It's still vulnerable to the same issues as the Yami's or anything else using only the raw water...

 

[haknslash]

I understand what you're saying but the engines are closed loop and that's how they describe it. I don't recall seeing any media stating the BRP boats or skis use a "full closed loop system for both engine and exhaust". They go into detail how their cooling system is designed and used, so I'm not sure where or why people would think the exhaust system was part of the closed antifreeze loop.

If Yamaha developed this system in the future, do you think they would include the exhaust into the loop? My gut tells me no but I'd love to see what they come up with. There really isn't much debate over which is better for engine cooling, otherwise we'd all be driving air cooled VW's

 

[smashedheadcat]

I get it... I just don't think it's fair to refer to the boat as being closed loop when only half of it is. It's still vulnerable to the same issues as the Yami's or anything else using only the raw water...

The exhaust systems share the same vulnerabilities, but the engines do not.

I understand what you're saying, neither are perfect solutions as they both come with their own compromises.

 

[morgro269]

I just don't think the manufacturers/ dealers do a good job of letting potential customers understand how the boats use the raw water. All they do is preach "closed loop, no dirt or corrosion, etc". I do believe it's intentional. Yamaha would probably do the same thing if they had this system (and I would be just as critical). 90% of potential customers are not as educated as the people on this forum when it comes to boats and how they work.

I showed my wife the Scarab website and their advertisements on Facebook. Then asked her if a Scarab uses any raw water. Her answer was "nope". Can't blame her either.

 

[ScarabMike]

Coolant cannot be used in a dual closed loop system with the exhaust manifolds for several reasons.

1. In the marine environment, raw water is used to "diffuse" CO2 gasses, and assist the engines emission system.
2. Raw water is used to cool exhaust gases and system to prevent overheating of the exhaust, and prevent ignition of possible fuel gasses.
3. Raw water is used as a secondary muffler to keep exhaust volume down

Im sure there are some exceptions, but they are very costly, and difficult to maintain.

 

[haknslash]

I just don't think the manufacturers/ dealers do a good job of letting potential customers understand how the boats use the raw water. All they do is preach "closed loop, no dirt or corrosion, etc". I do believe it's intentional. Yamaha would probably do the same thing if they had this system (and I would be just as critical). 90% of potential customers are not as educated as the people on this forum when it comes to boats and how they work. View attachment 25634

I showed my wife the Scarab website and their advertisements on Facebook. Then asked her if a Scarab uses any raw water. Her answer was "nope". Can't blame her either.

That screenshot tells you everything you need to know, literally in black and white. Notice it says "...damaging or clogging your ENGINE internally". It's not Scarab's, BRP, Seadoo or any other boat manufacturer's problem if people jump to conclusions or make assumptions. You say 90% of potential customers are not boat savvy yet those same people are shopping for something without doing research, especially when spending big coin? That fault doesn't lay on the feet of the manufacturer's!!! Further closed loop cooling for engine and raw water cooling for exhaust is not something "new" or something that was invented by BRP. It's been like this for a long time in the boating world, especially with inboard boats. Have a look http://www.westmarine.com/WestAdvisor/Exhaust-System-Basics

A "Full" closed loop system is more expensive to design and that buck gets passed to the end consumer. It's also not applicable on all engine designs and configurations for safety reasons. This is why you don't see it on most boats on the water and it's usually an aftermarket solution if you want best protection from corrosion, even then it depends if your engine and exhaust manifold can be configured for such a system.

I really think your issue isn't with Scarab or their marketing, which IMHO nothing you've posted would make me assume they offer a FULL closed loop system, but more so your issue and your wifes is that you don't understand this has been this way for years. It's "the norm" in most I/O configurations, so really this shouldn't be anything new. Look, I love the Yami boats over the others for a multitude of reasons, but I see nothing wrong with what Scarab is posting about their system. They are not lying or trying to play coy on words. If anything you will hear them mention "closed loop and engine" in their videos as well as their Facebook posts. Never have I seen them say "we offer a Full closed loop system for your engine AND exhaust". I think you're just misunderstood or perhaps don't know raw water cooling exhaust manifolds and mufflers has been in place long before Seadoo made skis or boats.

 

[Englewoodcowboy]

There is no true form of a full closed loop in marine applications. The closest you can get is like Pleasure Craft Marine used to do where the exhaust manifold was split into two components where it had a manifold and a riser. It was papular back then to cool the manifold with engine coolant however it required a much larger or in most cases an additional heat exchanger for obvious reasons. The raw water would pass through the transmission cooler, boat heat exchanger then to the riser where it exited out the exhaust. This was done because the manifolds where cast iron and did not have a very long life when being cooled with salt water, nowadays the entire manifold is made of stainless steel so they can reduce heat exchanger size and let the raw water cool the entire exhaust components. Now to say Yamaha's system is inferior is preposterous. This is the same cooling system (raw water) that has been used in their outboards since inception and it works extremely well with no incidents to my knowledge of corrosion failure so long as anodes remained in tack, this is also the same system that Mercury, Johnson, Evinrude etc. have been using for decades in all water types. Anodes (links) are equally important on all marine engines wether they are open or closed loop cooling as electrolysis occurs big time in the water. One big advantage of the Yamaha system or raw water over closed loop is maintenance these days. Let your coolant become acidic and get back to me when you have major internal corrosion issues. This simply cannot happen in a raw water cooling system on an aluminum block motor. Now if the block was cast iron, then yes the closed loop would be entirely superior for all corrosion resistance but it has a trade off, it has a mechanical pump and of coarse proper maintenance of the coolant itself.

 

[haknslash]

To further @Englewoodcowboy post, here is a good diagram showing you that even on a "Full" closed loop system, it's going to be water that goes through the exhaust manifold I most cases https://www.cpperformance.com/t-marine-closed-cooling-systems.aspx. However this water is cooled and has been cleaned (via strainer) prior to going to the hard parts. So there's not a worry with debris clogging manifolds or water jackets as mentioned earlier in this thread.

My point really isn't so much about the possibilities of a full closed loop system option existing. It's more about stating a "half" closed loop system has been around for years and that Scarab isn't trying to pull a fuzzy cover over your eyes and feed you lies. They're stating their closed loop system is designed for their engines, which is a true statement. Now if someone could show me where they are saying they use a full system then we would have a valid discussion about marketing lies and shenanigans. Personally I'm just not seeing it.

 

[Englewoodcowboy]

@haknslash I am not understanding what you are trying to point out to me. That diagram explains exactly what I described however the full system is typically found in marine diesels not gas engines these days. Now I am assuming you have never seen a sea strainer as it is a simple wire mesh cylinder that will stop large particles like grass and weed, it is just in an inline canister. The Yamaha's also have a strainer on the intake, the same as an outboard engine does however it is on the inlet rather than something inline so in your words it is filtered clean water.... BTW a typical sea strainer only catches things from about 1/16" in diameter and larger. See the example I am attaching of a typical sea strainer filter. They still allow sand and small particles which are easily passed through the system. In my entire life the only raw water clogged engine I ever saw was from someone running an outboard in the flats and it sucked up a lot of mud. I have never seen one plugged from typical use in all environments. I have been around boats my entire life, owned many built a few etc. and the raw water issue vs closed loop only became a concern when dealing with cast iron blocked engines. The fewer moving parts you can have in a boat the better as far as reliability is concerned.

 

[haknslash]

@Englewoodcowboy My post wasn't so much in reply to you but to the others who may read this thread. I'm in agreement with you. I was hoping my second paragraph would underline my intenions better.

Basically my point in this thread is to help others realize Scarab isn't lying to anyone or playing marketing games with people minds. They are stating exactly what their system can and does to help protect their engines. I don't work for Scarab, BRP or any marine engine company. Who cares if they market their cooling as a selling point? That's a good strategy from a marketing stand point and you best believe anyone in the business of selling boats would do that if it helps give them a leg up on a feature their main competitor is currently lacking. I don't fault them nor should anyone else IMO. I'm just calling it as I see it with no bias to any company.