Outboard Engine Sizing - Go big?

[FishingDisaster]

What's the better choice? A bigger engine than probably needed and ran normally under max speed? Or a decent size motor than is typically close to or maxed out.

In terms of engine reliability, service life, and fuel efficiency.

 

[dingbat]

Nothing worst than an under powered boat.

I go 3/4 rated HP at a minimum

I only run WOT a couple of times a season. The sucking sound coming from the fuel pump is bad enough at cruise speed.

 

[MTboatguy]

Go big, Spend Big, pretty simple equation to figure out. Bigger motors cost more to buy and maintain.

 

[JimS123]

As a poor college kid (and later as a young married with small kids) we bought small and lived with it. Now the kids are grown, the awesome pension has kicked in and we can afford anything we want.

When we recently ordered the new boat, the dealer said "we could have anything we wanted as long as we were willing to pay the price". We did.

Our old little boats many years ago were small and went slow. We loved them and wouldn't trade our experiences for anything.

Under powered is a state of mind, not a negative. If you are with the family and having the time of your life, why do you need more HP?

 

[ajgraz]

If you’re ever needing to outrun some weather, or push against some sea swell, you’ll want the extra power in reserve.

 

[Scott Danforth]

A big motor at light load is more fuel efficient tgan a small motor loaded heavily

 

[Sprig]

It kinda depends on the boat and what you use it for. But in general I always advise get the biggest motor available or the biggest you can afford. I’ve yet to hear anyone say they wish they would have got a smaller engine but Ive heard plenty say they wish they would have gotten a bigger higher horse power engine.

 

[roffey]

absolutely, go with the max.

 

[ahicks]

You really do have to figure out where your priorities are. There is no one answer fits all here.

Big motors that never do more than idle are a waste of money. On the other end, somebody interested in learning how to bare foot ski for instance, will likely tax the abilities of the biggest engines.

 

[Chris1956]

You want to barefoot, you need a 50+MPH boat, or really big feet...just saying

 

[jkust]

I guess I view this from a resources perspective. I see 3.0's in boats on my lake or rather hear them and generally they have a 3.0 for the simple fact that it was less expensive and their resources were diverted elsewhere...as an example.
If you can afford it then my take is get the bigger engine in particular with boats which tend to be kept longer than a 36 month leased car. Many times the bigger engine gets better fuel economy than the smaller and of course you just have more power when you want and need it.

 

[dgiles]

You want to barefoot, you need a 50+MPH boat, or really big feet...just saying

Barefoot speeds are only slightly higher than water ski speeds.

 

[Chris1956]

We slalom at 36MPH. Barefoot is significantly faster, depending on foot size and weight.

 

[capecodtodd]

I'd say it depends on the boat. Smaller engines =better gas mileage but running them fast and long will reduce their life span. At the other end, why carry around a big heavy engine that uses more gas if you are not going to need it?
I'm looking into getting a new to me boat and the boats are rated for engines from 200-300. I figure a 250 would be a good compromise.
I know 2 guys with ski boats with 350's in them and they use them to slalom with. My Stingray has a 135hp 3.0 and it cruises along nicely in the 25 mph range and I occasionally blow it out at 40mph.

I'd say if you have the option go with a middle of the spectrum engine rated for the boat you want.

 

[FishingDisaster]

Thanks all! My question was more about engine life. My F-150 gets mostly a light-foot on the 5.0 which is good for the engine and increases lifespan. If I had a V6 I would have probably blown it by now just towing the boat. Conversely, I've heard some supercar motors last longer when driven aggressively - its better for the engine.

More specifically, I'm looking at 17-18' deep-Vs. Most of which come with a 90 HP standard and have 150 capacity. I'd likely max out the 90 HP fairly often, but figure a 115 HP would barely ever reach top RPMs. Which would last longer?

 

[ahicks]

With a 17-18' boat, you really need to watch the engine's weight carefully for good performance (power to weight ratio). Yamaha and Merc 4 strokes take a huge jump when going over 115hp. Honda makes that same jump at 90hp. 2 strokes will have similar jumps but I don't have them in my head.

Don't worry about wearing out an outboard built in the last 10-15 years or so, especially a 4 stroke. If history is worth anything, it will show that many/most engines will be installed on a SECOND or THIRD boat prior to "wearing out".

In my experience, more of them suffer from stuck rings due to way too much time at idle/very low power settings.

 

[capecodtodd]

OP are you looking to go fishing or skiing? Are you looking at used boats or new? Most boats come new with an engine that has been matched to the boat according to the style of the boat.
A friend has a new 18' Parker CC with 115 hp outboard and that boat flies.
My 02 F150 has the 5.4 in it but the new Ford trucks are doing more with less and many have a V6 as standard equipment.
It is true that super cars should be driven as they were designed but where can one go 100mph legally outside the track?

With boats as well as car engines it is best to exercise them on a regular basis.
Running WOT all the time is not good as is running at a low speed for a long time.
A friend has an older Evinrude and his boat is on a river where there are strict no wake zones and he is forced to putt along until he gets to the ocean. There is one spot along the river where he can open it up and the engine usually puffs some smoke as he clears it out.

If you find a boat that allows an engine range from 100 to 150 hp a good compromise would be in the middle.

 

[dingbat]

A friend has a new 18' Parker CC with 115 hp outboard and that boat flies.

Speed is a very poor indication of the overall performance of a boat.

Anyone who has battled against a stiff tide/current or pounded their way home in a following sea could care less about how fast the boat can go in ideal conditions.

Should a storm blow up out of nowhere, you can never go fast enough....

 

[briangcc]

I go by the following....you can always run at less throttle but you cannot add HP out on the water when you need it the most. Get the largest engine you can (afford).

 

[aspeck]

My rule of thumb is to go as big as your budget will allow. You will learn to adjust where you need to be. If the boat has a 150HP rating I would want to be in the 115 - 140 or 150 range if I could afford it. My boat has a 150HP rating and had a 115HP when I bought it. It is a heavy boat and the 115 did OK, but when the engine blew, I traded it for a blown 140HP and rebuilt the 140 instead of the 115HP. I like the difference! Faster, more power, quicker out of the hole, and less fuel consumption. Almost bought a blown high output 150 this spring to rebuild and replace the 140, but budgets got in the way.