Reply To: Thrust, hp, and weight comparisons

[David Stanton]

I don’t have thrust numbers, etc, but your 30 HP, being a 2-stroke with fairly large cylinders, will likely provide noticably more low end torque for getting planed off and pulling up skiers than a new 4-stroke, as with 4-stroke engines only firing on every other piston stroke, they don’t have the oooomph on the low end. A new Yamaha 25 4-stroke with it’s HP rated at the prop, with the correct propeller, should give you about the same top speed, and will use a lot less fuel. In recent years, Yamaha has redesigned their 25 HP 4-stroke and reduced the weight. Other brands tend to be heavier because they go to 3 cylinders to get 25 HP or more. The 146 pound weight is not that much heavier than your long shaft 30 HP . Short shaft 30 HP is 113 pounds, so long shaft is about 120 pounds. I have a few 30-35 HP motors from the 1950s, and on my pontoon, have a 25 Yamaha 4-stroke (my wife wanted the quietness of a 4-stroke there after riding a neighbor’s 4-stroke pontoon), so I’m familiar with both motors. My personal preference would be to stay with your Lark, unless it’s a heavily used boat where quiet, reliability, and low fuel consumption are a high priority. If you pull a lot of skiers and tubers, the Evinrude will be better….but going to a lower pitch prop with the Yamaha, and/or dropping the trim pin down will make it easier to pull up skiers, but these items will give you a bit less top speed. With the Yamaha you will need adapter hardware to use cable and pulley steering, and I don’t know what all that involves; otherwise, you will have to get a new steering wheel with today’s single cable steering setup. The Yamaha will have an alternator, which is a plus if you don’t have the generator kit on your Lark.
Dave