300hp diesel outboard

[gford001]

It's basically an optimax, converted to run on low sulphur diesel. they say it shares 95% of the parts from the petrol optimax.
interesting tecnology, if you'd call it that......LOL

Col

Yeah.
They're not very good.....

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[GBC]

Petrol was mandated off ships years ago so diesel is the only option. The diesel outboards I’ve used have a wave of torque down low to throw you onto the plane and then the typical small rev range so they have zero top end. 300 hp without a gearbox or rev range is going to be boring as batshit.

[gford001]

Petrol was mandated off ships years ago so diesel is the only option. The diesel outboards I’ve used have a wave of torque down low to throw you onto the plane and then the typical small rev range so they have zero top end. 300 hp without a gearbox or rev range is going to be boring as batshit.

The smaller vessels run 90hp 2 stroke yammys with a seperate ULP tank for their RHIBs, maybe a couple thousand litres of fuel.
We also have a small RHIB on board with a petrol engine......
But it's only 50 odd litres, as opposed to the 1-2000 we would carry for bigger boats with ULP outboards....
Torque wise, these are almost opposite.
They're setup really poorly, engines way too high, so the cavitation is extreme. There is no low speed maneuverability, and takes a lot to get on the plane.
Flat out, in glassy conditions, they go pretty well.


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[gazza2006au]

The thing is i guess is the weight when u add one of these bad boys to your boat you'll be getting up there in weight 350kg+ engine u would want a big boat to counter balance all that weight especially if u hang one off a 2 foot long pod can u imagine the leverage on the transom? incredible...

[Paul071978]

Around the same weight as the 350hp yam

[gazza2006au]

Paul looking now i can't find a 350 Yamaha only 250's 253/259kg and 425hp 442/4six3kg but that is a V8

[Paul071978]

346kg for the 25inch shaft. Scroll to the bottom of the page. It’s the v8.
https://yamahaoutboards.com/en-us/ho...#specs-compare

[myusernam]

They are flat out making sterndrives that can handle diesel torque. Why you would try and use an outboard gearbox, hang the engine out the back and have dubious reliability when u can go with a proven solution (like a volvo IO) is beyond me.

[scottar]

Price, ease of maintenance and change over (part at least of who these are aimed at is a commercial market that regularly changes engines - sometimes even having a spare on the shelf ), the ability to tilt the engine out of the water properly, space in the cockpit - there's a host of reasons. That coupled with the storage issues associated with petrol and as expensive as they are, they will still find their way onto transoms. Stern drives are hardly a problem free beastie - there are plenty around who will never own another one. OXE use a totally different design that uses a mid mount gearbox and belt drive to get around the short comings of a "traditional" outboard.

[gazza2006au]

0What is fuel economy like on a I/O Vs Outboard? outboards are getting really lean these days and they are running on next to no fuel i picture a I/O just like running a car engine but they are Vsix and V8

[TheRealPoMo]

On a carbed 80's tech GM V6 with a 350 Holley I was getting 18l per hour at 24 knots in an 18.5 ft Fibreglass. I thought it pretty good.
42 knots increased consumption of both fuel and underwear markedly.

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