# Need help deciding upon a motor



## The Hamilton Guy (Aug 5, 2019)

Hey,
I have a wide body deep V Legend Boat with a 15 HP 4 stroke motor. 
I need to replace the motor. 

I am open to suggestions. 

I am looking at buying a new 20 HP or 25 HP Mercury 4 stroke. 
There is a cost AND weight difference between the two and I’m not sure if it’s significantly worth it to go up to the 25 HP motor. 

Suggestions?


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## lovedr79 (Aug 6, 2019)

if you can afford it, go with the 25hp. i wish i would have when i bought my boat.


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## Jim (Aug 6, 2019)

I have the same mentality, get the biggest one you can afford.

What is the weight difference?


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## The Hamilton Guy (Aug 6, 2019)

60 lb weight diff between 20 and 25 hp


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## DaleH (Aug 6, 2019)

More HP will bring that hull alive! I’d go lightest 25hp you could get, with BEST dealer near you, if buying new.


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## onthewater102 (Aug 6, 2019)

Trying not to get too verby in the response, but you're comparing two totally different machines. This is not just a 5hp difference that mostly comes into play at the top end of the RPM range like I achieved by converting an older 2 stroke 20hp to a 25hp with a carb change. There are a number of other mechanical differences between the two setups beyond the additional weight that are far more important.

The 25hp is a 3 cylinder vs. the 20hp which is only a 2 cylinder. The 3 cyl will develop more low end torque out of the longer cylinders (same bore longer stroke - just like a 383 small block vs. a 350), but it also has a lower final drive ratio (1.92 vs. 2.15), so that torque will be put to good use throughout the operating range as it will be turning the prop faster at any given RPM speed on the engine. This should translate to both faster pickup and a higher top speed using the same pitched prop as you're generating more power throughout the RPM curve.

I've used the Yamaha F25 2 cylinder 4-stroke which has 2 larger cylinders (2.56" bore vs. the 2.40" used in either Merc) and a higher final drive ratio (2.00). It doesn't have sufficient low-end torque to get a boat on plane quickly even though it eventually will spin fast enough to develop enough power to achieve a respectable top speed (27mph in a decked 1448 with 2 guys & gear). Even though the F25 weighs about 15lbs less than the Merc looking at the spec differences I'd absolutely go with the 25 over either the Merc 20hp or the Yamaha F25.


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## jethro (Aug 6, 2019)

Agree on biggest you can afford. It will reduce the possibility of buyers remorse. The cost issue is basically buy once, cry once.


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## The Hamilton Guy (Aug 6, 2019)

Buy once cry once!! Like that. 

I’ll go for the 25 HP. 
There’s a Mercury dealer near me and a Honda one too. The Honda’s more money, but are the Mercury motors still good enough to not warrant the extra expense of the Honda?

Also...I’m going to opt for a tiller steer, manual start and tilt, as my boat is a 14’ deep V wide hull aluminum boat. I guess I have prop options to pick once I get into the 25 HP range? How do I decide what kind of prop I need?


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## DaleH (Aug 6, 2019)

Use the *prop calculator* listed as a ‘sticky’ in the Motors forum. It is dead nuts!


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## The Hamilton Guy (Aug 7, 2019)

I’m planning to get a new 25 HP 4 Stroke Mercury. 
To save money I am planning to get the one with manual start and tilt. 
Some people say that would be too hard to pull start. 

Are the new 25 HP 4 Stroke Mercury outboards very hard to pull to start?


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## jethro (Aug 7, 2019)

The Hamilton Guy said:


> I’m planning to get a new 25 HP 4 Stroke Mercury.
> To save money I am planning to get the one with manual start and tilt.
> Some people say that would be too hard to pull start.
> 
> ...



4 Strokes are definitely a little tougher to pull than an older 2 stroke with no mechanical valve train, but it shouldn't be that tough. I do think that for resale purposes e-start on a 25 horse is a really good choice. If you think you'll never need to resale the motor, or at least for a very, very long time, maybe it's not an issue, but almost everyone looking to buy a 25 horse outboard is going to want e-start. Don't forget that the e-start motor will come with a charging system to keep your battery topped up. I don't think the manual start will but maybe? A charging system is a big bonus for the house battery which runs lights, bilge, graph, etc.


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## The Hamilton Guy (Aug 7, 2019)

Ah! The charging system is a good idea. That way I don’t have to worry about keeping the battery charged. 
Ok. Thanks. 


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## onthewater102 (Aug 7, 2019)

No - you'll still have to charge it between trips, the gas motor doesn't run long enough to recharge the battery from the drain of graphs & lighting, even though in theory it could. The amount of gas you'd burn just to run your outboard as a generator long enough would not make sense. It's a nice feature that if your battery ever gets low you still have a way of powering your nav lights or bilge in order to get home safe.


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## The Hamilton Guy (Aug 7, 2019)

As for the battery, the short shaft apparently can’t have the power tilt, but can have the power start. I learned it will still have a pull cord which is great if I need it. 
Other than the power start and a fish finder, the battery really won’t be needed for anything else. 

What type of battery would be best?

My boat has lights, bilge and a trolling motor but I never use them. 


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## The Hamilton Guy (Aug 8, 2019)

I’ve been told that for my 14’ Legend Deep V boat the extra 60lbs of the 25 hp motor over a 20 hp motor, on the back of the boat, with the short shaft might be too heavy and let water over the transom. It was suggested I’d be better off to just get a 20 HP 4 stroke with electric start. 

I’m thinking of going that route. 

Which make of motor is better, a Honda or Mercury?


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## jethro (Aug 8, 2019)

onthewater102 said:


> No - you'll still have to charge it between trips, the gas motor doesn't run long enough to recharge the battery from the drain of graphs & lighting, even though in theory it could. The amount of gas you'd burn just to run your outboard as a generator long enough would not make sense. It's a nice feature that if your battery ever gets low you still have a way of powering your nav lights or bilge in order to get home safe.



Wut? I don't charge the cranking house battery once during a year on either of my boats and they start the motor and run the finder and lights for hunderds of hours a season. The house batteries only get charged when they are removed from the boat in December. And with my 150hp I would know if the battery got weak at all, it's a V6. The little 25 honestly I don't fish hundreds of hours a season but certainly a few dozen and once again, the gas motor keeps the battery topped up nicely. The Helix doesn't like low voltage so I know it stays fairly topped up.

Am I just getting lucky? It's possible, I am an ignoramous when it comes to electrical stuffs.


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## jethro (Aug 8, 2019)

The Hamilton Guy said:


> Which make of motor is better, a Honda or Mercury?
> 
> Sent from my iPhone using Tapatalk



Most people would tell you stay with Honda, but I have had a half dozen Mercury motors so far and they have been fantastic.


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## The Hamilton Guy (Aug 8, 2019)

I just am new to outboards and wonder if in the 20 HP category, is there a clear better choice?


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## onthewater102 (Aug 8, 2019)

jethro said:


> The house batteries only get charged when they are removed from the boat in December...Am I just getting lucky?



Yes and no, you shouldn't leave a lead acid battery in a depleted charge condition for any length of time. Yes the battery is probably working for you, but you're probably shortening the useful life of it by not topping it off after each trip because it's not likely reaching a full charge off the outboard. 

That might not be true if you're trolling the entire time with an outboard running, but for anyone running and gunning and fishing on their electric trolling motor their starter battery is less charged after an excursion than it was heading out.


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## LDUBS (Aug 8, 2019)

onthewater102 said:


> jethro said:
> 
> 
> > The house batteries only get charged when they are removed from the boat in December...Am I just getting lucky?
> ...



I had the same thought as Jethro when I read your post. Figured it probably was fishing style. My motor is running practically the entire time I'm out. Very seldom is anything drawing off the battery when the motor is off.


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## LDUBS (Aug 8, 2019)

jethro said:


> The Hamilton Guy said:
> 
> 
> > Which make of motor is better, a Honda or Mercury?
> ...




Previous boat had a Merc 25 HP four stroke. I liked that motor a lot. Never any issues. Drove my 15' Klamath side console at 27 MPH. Small Mercury outboards are made by Tohatsu. That maker has some very good reputation. I now have a Honda 50 HP four stroke. I like it a lot too. But not a good comparison because being a 50 HP is it kind of a different class.


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## jethro (Aug 9, 2019)

LDUBS said:


> onthewater102 said:
> 
> 
> > jethro said:
> ...



Ah yes, I am sure that is a big difference. I am always on the motor as well. Even my kicker motor has a charging circuit.


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## hipster dufus (Aug 16, 2019)

The merc is a rebadged tohatsu. A tohatsu would be cheaper.efi is a plus. U get a pull start and an estate.


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## The Hamilton Guy (Aug 16, 2019)

I got the 20 hp Mercury with ego and electric start. 

The electric start is a nice feature that I didn’t have before, and I am liking it. 

The idle seems a little jittery but we will see how it goes. 


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## Crazyboat (Aug 17, 2019)

Damn, I bought too big an engine! (Said nobody ever).


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