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Old 12-23-2019, 10:54 AM   #1
mncruiser
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City: Bayfield
Vessel Name: Phoenix
Vessel Model: Mainship 390
Join Date: Aug 2017
Posts: 345
Dinghy power results (with a surprise twist!)

Greetings all! This is a follow up thread to one I had posted back in March. The TLDR is I was asking about power options for a yet to be purchased dinghy. As usual, you all brought your questions and opinions, always thankful for that!

I had meant to get to this post this last summer, but life and boating happened. Now it's cold, work slowed a bit, so here I am!

Here's the link to the old thread : http://www.trawlerforum.com/forums/s...hts-43369.html

BUT...don't spend too much time reading that. This is about results...with a twist!

I ended up purchasing a Highfield 310 Classic dinghy. I also ordered a 20HP Mercury 4-stroke EFI outboard. The big debate for me at purchase was the 15 vs the 20. It's the same engine, same weight, the 20 has a different computer and as the dealer described it "a 10 cent washer that allows more fuel to be burned" to make it a 20. Oh, and I think the 20 was $300 or so more.

I got the boat back in June after a few delays. I've got some video footage I'm meaning to post too about the dink itself, but overall, happy with the Highfield 310.

After the break in period, I wanted to get specific about some performance data with the setup. I used Navionics on my iphone for data. I picked a calm day, and while I'm on the St. Croix river up in Minnesota, I picked a larger pool with less current.

I'm about 250 lbs, I had the boat, 6 gals of gas, oars, seats, a few docklines, and a few "silver sissies" (Coors light) as fuel for myself.

After break in of about 10 hours. Apologies, the speeds are in MPH.
3/4 throttle - 17mph
Full throttle - 19.5mph

Not bad right? The setup seemed to be just great, and I had really no idea what to expect, but sounds decent right? NOW...THE TWIST!

About 2 weeks after this test, I get a call from the dealer. He's says he's really embarrassed, and is apologizing, not telling me why. Well then he tells me- " Say, that 20hp you have? It's actually a 15hp. The covers got mixed up in the shop". Wow ok!

After much more apologizing, he offers me I can keep the 15, he'll get me the right hood, and of course give me the $ difference. Or, I can come get the REAL 20hp. Well now I'm real curious. Sure it's another trip, and engine off, engine on...break in period again. So I decide I want to get the 20...with the option if I'm not happy, I get the 15 back. He agrees. So I do the swap.

Maybe the 15 was just fine...I feel like it was. But I'll always wonder. Same setup as before, same type of day. Maybe I brought 3 silver sissies with this time as a reward for all my hard work. But ok, here we go, the real 20 hp's data:

3/4 throttle: 20 mph
Full throttle: 26 mph

Nice surprise eh? I can say the 20 really zipped top end, and also seemed to get out of the hole and on plane quicker. I did run the 15 with my family in it, my petite wife, 2 kids (5 and 7) and it did ok. But same family load, even the kids commented how zippy it now was.

Those speeds were significant enough that I kept the 20. Seems like it was worth it!

I'm happy to answer any other questions about the setup. This spring, I'm going to do some longer fuel consumption runs, most of our stuff was short fun trips.

I do have to say the setup is fast, maybe a little too much for someone not ready for it? The Mercury setup is nice, you can tension the turning force of the engine itself, and the throttle tension. Also I've found that the tiller adjustment is awesome - You can angle it off to one side, really nice in this small boat so the tiller isn't in your stomach. The engine also has the shifter on the tiller (think sticking up like a gear shifter) and I wasn't sure about that, but it is real nice as slow speeds for docking, etc. Easy to be at idle speeds and go in and out of forward into neutral then reverse.

Anyway, hope this was informational. More to come if I can get my videos together!

MnCruiser
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