2004 Marlin Repower to 300 HP Successful!!!

[Ruffhouse]

Lost one of my Yamaha 225 HP's to the corrosion issue last month - they were 2004 engines with 250 hours on them....... so repowered this week with a pair of 300 HP Yamaha's. Put three hours on it now in the harbor for the break in period and wow it's a huge difference up from the 225's. The boat fully loaded with 2 tanks of fuel and water gets out of the water on plane in seconds, and so far, it appears that i'm achieving a min of 10% better efficiency. Got her up to 41 MPH a few nites ago and still had lots of throttle left. Gauges are showing about 3800 RPM, with a 25 knot cruise and 20 GPH.

The new gauges are also amazing.......looking forward to trolling with the new buttons.

Thanks to all the contributors on the forum for their posts which were extremely helpful in making the decision to upgrade.

 

[Tuna Man]

Congrats on the new engines. Please post performance details when you get them. Many of us feel the 300hp engines would be ideal if we ever re-power our Marlins.

 

[Fishtales]

Sounds sweet. Would like to see the numbers too.

 

[Ruffhouse]

Will do for sure.  I ran her this weekend and spent a day fishing and then returned to home port across the open water in flat conditions. Now have 15 hours on them so will track performance more closely after i complete  the 20 hour required oil changes and maintenance.  But preliminary performance looks great. I got to 50 MPH at WOT. I played with the throttles a bit and also with trim to try to find her new "sweet spot"  and it seemed to hover around 3850 RPM and 26 knots and about 20.5 GPH. My gut says it will end up being 10% more speed at about 10% less fuel consumption versus the 225's  But.... Let's wait till I get slack tides in calm conditions in July and will report back.  Stay tuned.  Pics below

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[onoahimahi]

Nice looking boat. It is interesting how performance can go up and fuel use go down with increased engine size.

It also will be interesting to compare these numbers to Tom T's (Sailfish98's) Marlin with the new G2 E-tecs once things get tuned it.

 

[1998sailfish]

Beautiful motors. Please post a image of the gauges on your next run showing us the GPH and speed at your best cruise RPM. Best of luck with the new motors.

 

[Tucker]

Does insurance cover any replacement costs when the original engines are ruined by corrosion?

 

[Ruffhouse]

Yes - happily post some shots of the gauges soon. Not sure on the insurance yet. It's been 4 weeks since i submitted the claim and have not heard back from the insurance company yet - but will update accordingly.

 

[Ruffhouse]

Here's the statistics below. I couldn't figure out how to upload photos here on this page so if I can figure that out I will add them.

I ran the boat today in flat calm conditions at slack tide. Aux fuel tank was full and water tank was full.

RPM: 3800
MPH: 29 (on yamaha guage)
GPS: 24.5 KNOTS
GPH: 18.9

RPM: 3900
MPH: 30 (on yamaha guage)
GPS: 26.0 KNOTS
GPH: 20.1

 

[fischer]

Those F300s seem to be the best four stroke for the Marlin and for that matter the 330. From what I've heard, pretty trouble free as well. I'm sure you're pleased!

 

[Ruffhouse]

Here's the photos of the gauges. Left gauge is MPH and right gauges are RPM. In the top centre is the GPS reading in knots. Top photo is 3800 RPM and bottom pic is 3900 RPM. For some reason these pix won't shrink enough to show the tach readings on the right..... Sorry!

 

[1998sailfish]

Based on what the gauges show, It appears that it takes 600 total HP from Yamaha ( 3900 rpm, 30 mph, @ 20.1 gph) to produce near the same economy as the Evinrude G2's produce with 500 hp ( 3850 rpm, 31 mph, @ 19.5 gph ).

Congrats with your re-power selection.

 

[onoahimahi]

From the photos:

3900 RPM: 26 kts = 29.9 MPH; 29.9 MPH/ 20.1 GPH = 1.49 MPG
3800 RPM: 24.4 kts = 28.1 MPH; 28.1 MPH/ 18.9 GPH = 1.49 MPG

which are pretty good numbers. Does the MPG go up any for RPMs under 3800? Your MPG sweet spot could be between 3500 and 3800 RPM.

What pitch props do you have - 17" ?

 

[Fishtales]

nice...
it appears to sit perfect in the water as well.
those engines look like the perfect match for that hull.

 

[megabytes]

Noticed your anchor is not mounted in the cutout so it will free fall. An idea why?
Love to have those engines! :goodjob

 

[Ruffhouse]

Yes the props are 17 inch.

The anchor you are referring to is in the poster above me Tom T - as I've got a rockna anchor.

I'll be out in the next few weeks and test some different RPM settings and see how the boat reacts and post the data accordingly.

Happy boating thus summer to all. .

 

[Tucker]

Cheez, I didn't notice that. I was blinded by the shine of the hull

 

[ocnslr]

Based on what the gauges show, It appears that it takes 600 total HP from Yamaha ( 3900 rpm, 30 mph, @ 20.1 gph) to produce near the same economy as the Evinrude G2's produce with 500 hp ( 3850 rpm, 31 mph, @ 19.5 gph ).
Congrats with your re-power selection.

I'm not jumping in on your G2's are better comment, just want to point out that the max horsepower of the installed engines only comes into play when you are at the peak of the HP curve.

If you assume similar thermal and mechanical efficiency, then the engines are converting about the same amount of BTUs (i.e. gallons of fuel) to HP to drive the boat at a very similar speed. The difference in RPM and speed can be attributed to differences in lower unit gear ratio and/or props, and most RPM gauges round up or down to nearest 50 increment. The three (3) percent difference in fuel rate is within the measurement tolerances of the installed equipment.

We could, of course, get precise measurements of air temperature, atmospheric pressure, fuel rate, complete fuel analysis, boat weight, bottom paint/cleanliness, put on matched props, etc.

And I think the choice would come down to which engine color and exhaust tone you preferred.



Brian

 

[onoahimahi]

I'm not jumping in on your G2's are better comment, just want to point out that the max horsepower of the installed engines only comes into play when you are at the peak of the HP curve....


.... And I think the choice would come down to which engine color and exhaust tone you preferred.



Brian

These are both great engines and I'm not going to claim one is better than the other but this is HUGE for supporters of 2-stroke technology - the E-tec G2 equipped Marlin is achieving a steady 1.6 MPG at 33 MPH..!