Mercury 15hp vrs 20hp outboard

Blueone

Blueone

Well-Known Member
SILVER Sponsor
Jan 24, 2007
13,767
Lake Erie, Ohio
Boat Info
2004 420 Sundancer
Engines
Cummins 6CTA 450's
We are looking at a new dinghy this year. I am more or less settled on a Highfield CL310 http://www.highfieldboats.com/classic-310/# It is aluminum hull and weighs 132lbs. Max outboard size is 20hp.

Looking at the 15hp and the 20hp Merc they are identical displacement and weight. I have run into this before where the lesser hp motor is just a tuned down version. The difference in price is $500.

Do any of you know if I will really notice the extra 5hp?.... can you tune up the 15hp to 20hp if you wanted to ?
 
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I have a new Achilles 310AL with the Tohatsu 15hp electric start and it is more engine than my dingy needs. Look at the price difference mine and Mercury... They are made in same plant.
 
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The Bill Collector said:
I have a new Achilles 310AL with the Tohatsu 15hp electric start and it is more engine than my dingy needs.
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Your Achilles is almost identical to what I am looking at. Are you happy with the speed and size?... we are mostly just 2 adults but would like it to perform well with 4 adults.

and is the electric start worth the battery effort and additional cost all be it very little?
 
I have a West marine 11.5 ft hypalon weighing 160 LBS with a 15 hp Mercury this combo gives me plenty of speed and planes very quickly.
 
Caseclosed said:
I have a West marine 11.5 ft hypalon weighing 160 LBS with a 15 hp Mercury this combo gives me plenty of speed and planes very quickly.
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What davit system are you using?.... I was thinking the 11.5' would be a bit big blocking access to the swim platform door?
 
Blueone said:
Your Achilles is almost identical to what I am looking at. Are you happy with the speed and size?... we are mostly just 2 adults but would like it to perform well with 4 adults.

and is the electric start worth the battery effort and additional cost all be it very little?
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With 2 adults it gets a plane quickly and no issues. With 4 adults I do no attempt to plane. Our previous dinghy was pull start and not a big deal but for a few extra bucks it's now push-button and I added a USB & 12volt outlet into the top of the battery box. So, in short get the electric start and you won't regret it.
 
We would have been fine with a 15hp, but when we had family over, I was happy to have the 20hp. Something very satisfying getting on plane with 4 adults and 2 kids. 15hp wouldn't have done that!
 
My boat has the hydraulic lift platform.12 ft is the the max boat that will fit on the platform.Total weight of my dingy is 270 LBS.
 
Blueone, a good friend in the marina got the Highfield last year. It is a nice set up and he runs the 20hp Merc.
I only have a small 10hp Merc and I am looking for a 20hp this season, but where we are located, we travel pretty far in the dink(s) and will spend all day (8 to 9 hours) running around the bay and bars.
If it were me and the dink is rated for it, I would always go for the more hp. If / when you add a couple of adults the extra power will be handy.
 
Brent Nutting said:
I only have a small 10hp Merc and I am looking for a 20hp this season
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I am impressed with the new design from Mercury for the 20hp...the tiller is pretty interesting...oil change/canister and weight are plus's too
 
Blueone said:
We are looking at a new dinghy this year. I am more or less settled on a Highfield CL310 http://www.highfieldboats.com/classic-310/# It is aluminum hull and weighs 132lbs. Max outboard size is 20hp.

Looking at the 15hp and the 20hp Merc they are identical displacement and weight. I have run into this before where the lesser hp motor is just a tuned down version. The difference in price is $500.

Do any of you know if I will really notice the extra 5hp?.... can you tune up the 15hp to 20hp if you wanted to ?
Click to expand...
We have had the Highfield 290 for 3 years now we started with a 9.9 mercury which worked OK but with the short hull length it was sometimes difficult to get two people on plane quickly especially in rougher water last year I switched to the new 15HP EFI with the cool center mounted tiller it works perfect I top out at 20 mph WOT with one person haven't checked it with two but it can't be much different, I would recommend the 20 HP for the 310 like you said the weight is the same, I would go with the electric start if I had to do it over again.
Rick
 
From my experience, it would be cheaper to buy the 20HP now, rather than "modify" the 15HP to be a 20HP later. One way to check is to compare parts lists (and part numbers) between the two engines. See what things are different and the costs associated with each. Account for labor either by paying someone or taking into account how much your time is worth.

You might consider Smart Tabs, if needed. They would make a VERY noticeable difference in hole shot - regardless of the engine. Not expensive, either.

One thing I've learned over the years... NO ONE in the history of boating has ever said "Shoot, I should've bought the smaller engine". :)
 
Oversized and under-utilized rather than undersized and over-utilized ??? I'm very happy with my 15hp and when it's just me, I have scared myself a couple of times...lol
 
Lazy Daze said:
From my experience, it would be cheaper to buy the 20HP now, rather than "modify" the 15HP to be a 20HP later. One way to check is to compare parts lists (and part numbers) between the two engines. See what things are different and the costs associated with each. Account for labor either by paying someone or taking into account how much your time is worth.

You might consider Smart Tabs, if needed. They would make a VERY noticeable difference in hole shot - regardless of the engine. Not expensive, either.

One thing I've learned over the years... NO ONE in the history of boating has ever said "Shoot, I should've bought the smaller engine". :)
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Agree with all of this, but go with the 20hp, and I doubt you will need the Smart Tabs. Not sure you need electric start, as the EFI starts easier than any carb engine. BTW, have you looked at the Suzuki? I have had one for 4 years now, simply an outstanding motor. They got into the EFI in the smaller motors early on, and it shows. Outstanding piece of machinery.
 
The Tohatsu 9.9, 15 and 20 are identical engines. The difference is in the ECU and an intake restrictor. A new replacement ECU can be had for around $800. I plan to upgrade my 9.9 to 20 this winter.

Tohatsu makes the small Mercury engines, so I would bet there is a similar upgrade path. All that said, it's more cost effective to buy the bigger engine up front, than to retrofit it later.
 
The 15hp will NOT plane with 4 adults, just tried it last weekend, get the 20hp. That being said the new tiller handle with shifter is nice, I'm very happy with mine
 
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That new Mercury looks really nice. It might be enough to convince me to trade up from my 2 stroke Evinrude. The biggest reason I have a 2 stroke is for the weight savings over a 4 stroke. At 99 lbs that difference is really close now. EFI? Yes please - not looking forward to another carburetor rebuild. The adjustable tiller looks fantastic.
 
To close this out for now :)… I have been going back and forth and wasting my summer away so I decided not to try and put a big dinghy on this boat with manual davits. I will wait until I have a hydraulic swim platform.

So I bought a small Zodiac Aero 270 ...I have had good luck with them, 5 year warranty and cheap enough. Its the right size to pull up on the swim platform without davits and tie down with little effort.

Aero.jpg


I have always had a Tohatsu 4hp....that I converted to a 6hp. Its been sitting for a couple years so changed the oil, new fuel filter, fuel pump, spark plug, new coil and took the carb apart and cleaned it..... runs like new now

Tohatsu.jpg


Then I bought a bad ass prop for it....1" in diameter bigger and 1" more of pitch... I am leaving the 4hp sticker on it so its a true sleeper :)

prop.jpg


Should be good to go now to putt around the marina... and win some races :)
 
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