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Twin 250 hp Tohatsu are now installed- GW 28 marlin

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Twin 250 hp Tohatsu are now installed- GW 28 marlin

Old 01-30-2019, 04:06 PM
  #21  
efx
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I removed year 2000 Yamaha 250 hp ox 66. The CL to CL was 28.5". I was lucky I could reuse the existing bolt holes. Image of them is below. These old gals never let me down!

Last edited by efx; 01-30-2019 at 04:15 PM.
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Old 01-30-2019, 04:15 PM
  #22  
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Old 01-30-2019, 04:19 PM
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MPG improvement?
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Old 01-30-2019, 04:42 PM
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Nice to know same center to center. Makes it easier.
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Old 01-30-2019, 04:47 PM
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I've only had them running for two hours and that is at low speed per the break in procedure. I do expect to get 16-20 gph at 4000 rpm.

The 2 strokes were good but your really had to watch them, I could easily go 40 GPH if i wasn't careful.

Bottom line is that if i stay a cruising speed of 4000 rpm with the tabs partially down and cruise smartly, I can double my fuel efficiency. The technology is 18 years newer.

I don't care about speed. I like efficiency, reliability, and low noise.
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Old 01-30-2019, 04:54 PM
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Center to center spacing was set up by grady white back during the first install of the motors in 1993. The tohatsus are the third set of motors and the 28.5" worked out perfectly. Good foresight GW.
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Old 01-30-2019, 05:18 PM
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very nice. that was a great deal. keep us posted.
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Old 01-30-2019, 05:38 PM
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I have a 30 HP 4 Stroke Tohatsu model year 2002 and it is still running flawlessly. This thing has been rode hard and put away wet, more than once.
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Old 01-30-2019, 06:46 PM
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Originally Posted by efx View Post
I did notice that also. It seems like my electronics were steady and my battery charger didnt kick on full when i put shore power on. It seems the engines are charging the batteries faster than the 2 strokes. These engines do have alternators on them versus stators which seems a good idea!
Alternators also have a stator. Inside of them.

Pros and cons of both belt driven alternators and permanent magnet generator electrical systems. Tohatus, being based on a Honda, and Honda being in the automobile business, is apt to use an alternator.
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Old 03-21-2019, 04:45 PM
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Here is an update on the motors.

I am at 12 hours now. The break in went perfectly. I followed the manual exactly and used 100% fresh gas.

The first trip was primarily idling, then each successive trip went up each increment of RPM and percentage of higher RPM.

Then I did a long 75 mile run back and forth to the island with a night break. The run had intervals of higher speed and slower speed. I didn't baby them. They are getting faster and faster. The sweet spot seems to be 4100 RPM for a clean 29 mph. I am getting approximately 1.7 mpg in calm following seas.

At WOT lightly loaded I am hitting 6200 RPM ( they are rated at 6300 RPM max) and 41 MPH. Here is a photo. I am going to start playing with props now to get the most fuel efficiency. I really like to run at 30 mph as it seems that you are getting somewhere!


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Last edited by efx; 03-21-2019 at 04:51 PM.
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Old 03-21-2019, 05:04 PM
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Interesting covers. I presume they have mesh inlets to allow air to the motors when running? What brand please?

The motors look great.
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Old 03-21-2019, 05:13 PM
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Oceansouth is the brand and yes they have very nice mesh covers at the openings and have a felt liner on the inside. Really good fit and straps
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Old 03-21-2019, 05:20 PM
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1.7 MPG......I hate you.......lol...
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Old 03-21-2019, 05:41 PM
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Originally Posted by alloyboy View Post
Interesting covers. I presume they have mesh inlets to allow air to the motors when running? What brand please?

The motors look great.
what for are those covers?
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Old 03-21-2019, 05:43 PM
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I would have guessed that you would have had a higher WOT speed than 40 mph. What was you WOT speed with the OX66s?
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Old 03-21-2019, 05:51 PM
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Where are you located, OP? Congrats on the new engines, I hope they serve you well. I can't imagine however that re-powering with Yamaha's would have been $20k more?
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Old 03-21-2019, 06:09 PM
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Great motors! We have one on a TowBoat 2 years old... 1041 hours... nothing but normal maintenance!!
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Old 03-21-2019, 06:51 PM
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That's awesome! I would have gone that route if they had a 300. You can't beat Honda! Just put a 300 Zuke on my Grady. Still in the break in but cruising at 25 I was burning 8.6gph.

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Old 03-21-2019, 10:21 PM
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Originally Posted by Toothpick 10 View Post
I would have guessed that you would have had a higher WOT speed than 40 mph. What was you WOT speed with the OX66s?
as a baseline my marlin 28 topped out at 38kts with Suzuki df250s. Not built for speed with a 10-1/2ft beam
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Old 03-22-2019, 05:35 AM
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I used one of those oil vacuum systems via the dipstick tube on my Suzuki 300's on a previous boat. It was a little slow but it worked very well. Just make sure the hose will fit into the dipstick tube. It barely fit in the Suzuki.
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