15hp vs 20hp

[mwb.wright]

Hi Guys,

Is there much difference in a 15-20hp Mercury (new) engine? - 4 stroke.

The SIB it will be going on is a Mercury 365HD.
Most people on here are running 20-25hp.
One boat dealer is saying no more than 15 and the other is recommending a 10 - which is far to small.

Is there much in them as one dealer is stating they are the same engine but the latter detuned?

Was going to wait until after Xmas for 'better deals on the motor' but seems better to get both at once from the same dealer as some benefits from this may be had.

What size would you guys recommend?

Boat will be trailered but want to cart the engine in and out the truck.

Another option is to scout for a decent 20-25hp 2 stroke? - pros and cons for either.

I'm wanting to do a a bit of missioning with the motor (around Anglesey and so on) so needs to be reliable.

Many thanks.

[Fenlander]

From my experience with a heavyish alloy floor 3.5m Honwave and 15hp I'd prefer the 20hp on that Mercury which is an even heavier SIB.

Also the 15/20 Mariner weight the same... a rather hefty 52kg so in my book no point lifting the weight of a 20hp for only 15hp power.

If you are buying new then consider the 44kg Suzuki 20hp... that was my choice earlier this year after loads of thought.

A mint 2006ish 20/25hp 2-stroke is another viable option.... down to personal choice.... would save you a grand though!

No don't get a 10hp... you'll be disappointed.

[Max...]

SIB engine advice never changes, the rule is simple!

Buy the biggest engine you can physically manhandle* from your car onto your boat.

*without dying/rupturing/collapsing yourself.

[stevo]

i use both a 15hp yamaha and a 20hp yamaha both two strokes though the 15
is easier to handle at 36kg it pushes my 4mtr avon well but when the 20hp is on it makes it fly even with three big lads on.

[kaman]

Hi MWB.
I believe the Mercury engine to which you refer is the same as my Tohatsu 20hp 4 stroke .
Bought it new in 2010 as a 15hp unit.
Changed the carb for just over 230 quid soon after to uprate it to 20hp.
As a 15hp pushing my Honwave 3.5ae sib it was fine one up.
It still got on the plane with my mate on board - we are both 6ft 2 inches tall and between us and gear carried, there will be well over 40 stone onboard. We had to move our body weight around as it struggled to get on plane.
With the carb change it revs slightly higher and there is a sharper throttle response under load.
It planes easily with my mate and I now.
Very easy job to uprate and actually probably saved money on going straight for a 20hp from the outset.

[paddlers]

We have the Honwave 3.5 AE. Currently running a 20 hp Tohatsu 4 stroke which gets 5 of us (62 stone ) on the plane with no issues.
The 15 hp Mercury 2 stroke wouldn't.

It's a heavy lump to manhandle but worth it when it's on. Quiet, economical and reliable. Personally I'll always go for maximum hp as you can always ease back on the throttle which has to be better than revving the nads off an engine.

[WhiteShark]

I have the new 20hp Mercury 4-stroke. It felt extremely heavy at first but you get used to it and now I find it relatively easy to lift out of the boat locker and lower down onto the Aerotec when it is doing double-duty as a tender. Actually quite easy to lift out of the car boot and carry down to the beach when SIBing now I have the muscle memory for it. The carrying handles are much better positioned than the Yamaha equivalent, which is why I chose it over the Yam. It is a quiet and reliable motor with decent low down grunt. You'll be pleased. The 15hp and 20hp are identical apart from carb, gear ratio and prop size IIRC. Cost considerations aside it doesn't make sense to get the 15hp over the 20 if your boat is rated for it.

[mwb.wright]

Thanks for all the feedback!

I think it's pretty clear the 20hp is the best option, same weight more power and a few hundred more which will save the mess about of trying to up the 15hp in the long run.

I take it from the feedback that these motors can run all day etc as I mentioned before I plan on doing some pretty longish routes.

I hope this 53kg isn't going to be a killer haha.

[paddlers]

I find mine awkward rather than heavy. If you have someone to pick up the skeg/propeller end it's a piece of cake putting it into the car boot. It's the top-heavy aspect that makes the 20 more of a handful.

[Duggy]

My newly acquired 20 hp 4 stroke feels exceptionally heavy but I'm assuming that's me being out of practice/a lot older/extra careful to when I think back how I was when I had an old 15 hp 2 stroke over a decade ago.

[kaman]

My old man has a 1970s Yamaha 2 stroke 15hp.
It is light as a feather compared to my de - restricted Tohatsu 15hp 2010 4 stroke.
I regretted getting a 15hp almost right away as my Sib struggled to plane with any weight onboard.
From the outset I knew that the option to change the carb was always there if the 15hp was not enough. There's not a massive gulf in power output bwtween 15hp and 20hp but if your going to put your back out - you might as well do it lifting a 20hp.

[jeffstevens763@g]

All above sound advice I run the same boat with a 25 Suzuki I could have managed easily with a 20 but I went for top hp which means I have the ability to cruse at low revs at a descent speed.as for transporting for me no point in lifting when you can make up a sack barrow to transport then the weight difference is insignificant 15@36 kg up to 25@61 kg 25 kg between them and if you drop it whilst carrying more problems?
To be honest the Mercury is a boat to trail too heavy to and awkward to keep setting up. IMO