Power for a restored 18SF

[pjzabo]

Guys - this is great information. I usually do quick runs with 2 on board, 3 at most. That's the reason I got this old 18SF. I have a 2006 24' Robalo with a Yamaha 250 and it is a great boat, but more than I need 90% of the time and that heavy tank burns a lot of fuel (it really needs a 350). I thought my whole family would get into the boating thing but it is usually just my son and I and my wife and 2 girls stay home.

I usually only get 4-5 hours on the water (working for a living sure does suck) when I go out I usually stay within a 5-10 mile radius of my home port. I like to get on the fishing fast and not waste time moving around, so an efficient 30mph cruise is a big plus for me.

I am a big guy (6'2" and 240 lbs), maybe I should just lose 50 pounds and get the bigger motor, lol. Sounds like the E-tec is the ticket. Maybe the 130HP at 390 lbs. I also plan to mount the batteries in the console and keep the boat real simple and lean. I am not going to raise the floor since it is sound and firm, boat has a fresh transom and tank, I just want to focus on power, electronics, wiring and details.

[Fr. Frank]

Denny and others are right about stern weight. In addition to what has been said, with the amount of hull rocker on the 18', having extra weight on the transom will cause excessive fulcrum effect: causing the bow to lift very high in only a small swell. The stern will ride okay, but the bow will bob up and down a lot. You end up sacrificing some speed/economy because you have to trim the engine in more to get the softer ride.

I second the idea of the 1.3L 3cyl. 90 at 335 lbs and $7,600, or 1.7L V4 115/130 Etec at about 390 lbs, and $7,900 and $8,800;
or the 1.5L 3cyl. 115/125 Optimax at 375 lbs. and about $7,700 and $8,600

A 115 hp motor can give you a solid 30-32 mph cruise on the 18 SeaCraft. But be aware that both the Etec and the Optimax are actually HPDI 2-stroke motors, NOT 4-strokes.

The lightest of the 4-strokes are the 115 Yamaha at 402 lbs and $8,300, and the Mercury 115 at 399 lbs and $8,100.

IMO the Zuke 115 at 427 lbs and the Honda at 505 lbs are just too heavy.

Hope this info helps.

[eggsuckindog]

My 18 was fine with 115 but I wouldn't have wanted less - although my inline only weighed in at 268 - my 200 Merc is just over 4oo and the scuppers are pretty wet in a 20. You can't go above 400 in an 18, that 140 Zuke seems pretty nice or the 115/130 etec - the Etec will outperform all others but may cost a bit more but power to weight and fuel they really have no equals today.

[Snookerd]

so I'm a little biased towards lighter motors.

I agree with Denny! After 3 different configurations on 2 different 18SF's, I will tell you that the 130 Yamaha 2 stroke is great power and weight - as ASDFhood will attest. The 150 carbed 2 stroke will push you close to 50 propped right. The Zuke 140 will work ( I personal use on an 18SF currently), but I think the 140 Zuke is too heavy. Weight is the most important detail. I would stay under 390 lbs.
A 1974 18SF is able to handle to 140Zuke better than a 80-87 pre-Tracker hull. But as Denny said, weight is my primary focus, power is next. A 90 -115 4 stroke @ 400lbs or less would be my choice for newer power.

[pjzabo]

OK - I was sold on a 4 stroke, but now I am not so sure on this boat. Another consideration for me is price. Ideally I am getting a low hours used engine and I was targeting something 5-6 years old. Focusing on just the 2005 model year and being sensitive on weight narrows the field a lot I guess. Leaving me looking at Yamaha's 115 2 stroke (I think they stopped making the 130 in 2002) at 367 lbs, or their 4 stroke at 412 lbs. Suzuki's 115 4 stroke is 416 lbs. The Etec 115 is 369 lbs. That Etec does look perfect for this boat the more I read and look at it. If I could find one around $4000 with controls and instruments I would jump on it.

[McGillicuddy]

At 115 hp, I don't you will find a used e-tec for 4K.

A used optimax, maybe. But it will be 2003 or older and be very well used.

A 2 stroke Merc 125 might also be a nice match seeing that you like to run to the grounds, fish, and get in. Its an interesting motor that I've been considering because its light and has generous hp rating.

Caveat is they run on 2 cyl. til they hit 1800 rpm and then they stumble to 4 cyls and take off like a bat out of hell. Thus the 10-20 mph might be hard to manage speed.

Do some searches on Merc 2+4... Won't get the economy of a direct inject, but they troll and idle without loading up. And run with power...

[asdfhood]

Just a note about performance, with 2 persons on board, 45 gallons of fuel, no bimini, a large cooler full of stuff, and fishing gear I cruise at 29/30 mph and 3900-4000 rpm. WOT 5400 rpm and 43 mph. This is from gps readings. I can't shed much light on fuel consumption as the gas gauge doesn't work and I hav'nt kept close enough records to make even an inaccurate estimate.

[pjzabo]

I'll research that Merc, but on the surface the 2+4 kinda scares me. NADA price guide lists retail on a 2005 Evinrude 115 as $4200. I guess these things are usually off market and that must be a desirable used motor if you can even find it.

[pjzabo]

Another question - has anybody tried using an Armstrong flotation bracket off the back of an 18SF? This should help with the weight of the engine and the the back splash issue, no? I'm used to seeing them on larger 20+ foot boats, but wouldn't the 18 SF benefit from one?

[Bushwacker]

Another question - has anybody tried using an Armstrong flotation bracket off the back of an 18SF?

KEYSCRUZ has an aluminum bracket with a 150 E-Tec on his 18; don't know if it's an Armstrong. You might try sending him a PM, but haven't seen him on the forum lately.

This should help with the weight of the engine and the the back splash issue, no?

NO! Moving the motor aft of transom will shift CG aft and make the boat balance issues Fr. Frank described even worse! A light weight motor is even more critical with a bracket! All the flotation tank does is help keep the powerhead out of the water at rest. Once the boat is on plane the flotation tank is out of the water so it has no effect. The Hermco bracket has the most flotation of any bracket because bottom of tub comes straight back from transom and doesn't slope up like the Armstrong.