outboard size vs. weight

[tav]

i will be looking for a 2 stroke (possible a 4) 9.9 or a 15 h.p is there any weight difference between the both? and the older i go on the motors will they be heavier? aposed to the newer one 1990 and up, i do want to stay with a newer one mainly with a shut off landyard and lighter on the wgt.

my 14" loew 1457 "V" has a max of a 15 h.p can i go with the max or should i stay under that ?

thanks you.

 

[RotaryRacer]

Re: outboard size vs. weight

Actually, it seems like motors are getting heavier. That is partly b/c 4 strokes are more and more popular. Emissions controls and fuel injection add weight also.

Carbureted 2-Strokes are definitely the lightest option. If weight is the primary concern, a 2-stroke Johnson/Evinrude or Mercury would probably be pretty good and relatively cheap.

If you can afford a 15hp get it....you never say, "I wish I had less power". The boat is rated for it so there should be no issue....as long as the motor isn't too heavy for the boat.

 

[tav]

Re: outboard size vs. weight

well the spec plate say max 15 h.p but how would i know or find out if a 15 h.p is to much wgt. for that boat?

 

[seabob4]

Re: outboard size vs. weight

well the spec plate say max 15 h.p but how would i know or find out if a 15 h.p is to much wgt. for that boat?

If the boat is NMMA certified, the specs used to determine max horse are really based on weight, not HP (per NMMA S-30, for those who are interested), as they list a HP amount the builder wants to install, then the corresponding weight is factored into the boats rating.

Builders also have to perform tests at WOT to see if, at WOT, certain requirements can be met. Collision avoidance, hardovers, etc. If these requirements can't be met, placards must be attached stating various seating areas are not to be used at speeds over X MPH.

That being said, most 15s use the same block and components as 25s, therefore weigh the same. So go with the 15, run her for a while. I had a 25 Merc on a 14' Alumicraft and ended up putting a 40 Evinrude on her. Loved that boat. Hell, my buddy just hung a 115 Yamaha on a 16' Proline...

Never enough power...

 

[Texasmark]

Re: outboard size vs. weight

My personal opinion is to buy the largest engine of a series for the best weight to power ratio. Looking into a '94 Mariner (Merc) sales brochure I happen to have, all things being equal:
4-5 hp 6.2 cu in,
6-8-9.9 hp 12.8 cu in,
20-25 hp 24.4 cu in,
50-60 hp 51.8 cu in,
75-90 84.6 cu in,
100-115-125 hp 113 cu in,
135-150 hp 121.9 cu in,
in the V engines:
150-150 Magnum-150 EFI-175-175 Magnum EFI-200-200 Offshore-200 Magnum EFI-200 Offshore EFI 153 cu in. (that's 8 engines with the same similar weight/size and all),
225-225 Offshore 185 cu in,
275 Offshore 207 cu in.

Total weight and lower unit size follows the same philosophy as the cu rating. When it changes, the lower unit usually changes too....gets beefier as cu in bracket goes up.

That's the way I see it.

Mark

 

[RotaryRacer]

Re: outboard size vs. weight

That being said, most 15s use the same block and components as 25s, therefore weigh the same.

Good information in your post...however, the statement I quoted isn't true. The Johnson/Evinrude motors from the 70s-90s have the same block for the 9.9-15 hp motors. The 20-35s are the next size up.

I also thought that Mercury used a similar approach to motor size and HP.

 

[Texasmark]

Re: outboard size vs. weight

I also thought that Mercury used a similar approach to motor size and HP.

Thats what I provided. Weights remained constant for the engine sizes which says that the smaller engines are just choked down versions (carb/timing changes) from the larger units of the series.

The only place I found weight variances was in the high hp units where EFI or Magnum added some extra features that caused the weight to vary slightly (like 10# on a 400# engine).

Mark