How loaded do you plan using that combo ? Which type of water will the combo be encountering, flat ones, windy, choppy, with strong currents ? Depending on the answer min 9.8, 9.9 - max 18, 20 HP long shaft outboards with maximized props.
For a 19 footer 10 HP is optimum. It will take you to hull speed. You can add more HP but it won't make the boat go much faster. If you already happen to have an 8 HP, give it a try before you go bigger. A 6 would be too small (tried it on my 19 footer)
The most logical setup is mounting it on a retractable bracket. Your Sunrunner's transom is quite similar to my Stingray., Buy a short shaft. It'll sit down nicely with the prop in the right place, and it'll also lift up high enough that the lower unit will be out of the water when underway with the main engine.
Switch to the lowest pitch prop available for the engine you use. Some manufacturers call them "sailboat props" or auxiliary engine props. You won't be able to plane the boat, and your rpms "probably" won't reach the "normal" operating range, but you do want the motor to rev as fast as it can .
For me...I have a 19ft cuddy and although my 8hp yamaha is terrific as an auxiliary, Ive had a 4hp on it too and does just fine.
the most important thing is to get the height set up correctly. I’ve found a short shaft is idea as long as you get the prop in the flow of water under the hull. A long shaft can drag in the water when on plane and tilted up. Also means I can use the short shaft same motor on the inflatable too. A long shaft is no use for this.
remeber the bigger you go, the heavier it is to put on and off and the more it will affect the way your boat sits in the water. Also more strain on the bracket and transom too.
But more than anything I can’t stress how crucial it is to get the height correct. You could have a 20hp on it but if it’s not low enough it will do nothing but pull whirlpools of water and air from behind the transom and surface of the water. Not to mention blow the rpm sky high when it does this. Very important.
Ive got a 5hp Merc on my 18 footer . I dont put the boat in the water without it. Love it for just slowly cruising or trolling, it pushes my boat just fine.
plus its great to have in the event of the main engine going out.
Owning any low range HP kicker is fantastic compared to owning none. A friend of mine that owns a large and heavy high hull boat with recurrent main motor issues bought a 2 strokes 9.8 HP kicker. Main failed 15 miles off coast, started the portable kicker to find out that due to strong winds and water current was still drifting towards Easter Island at max throttle kicker range.
If he had follow my recommendation to go straight towards a spot on less pitch prop maximization for motor to rev to it's full rpm range other would have been the end result. The Coast Guard fined him for putting in jeopardy the lives of others along the cost expense for towing the combo back to terra firme as well. Boaters usually doesn't follow proved recommendations given by others until unlucky events as described happens...
If your main motor has recurrent mechanical issues, installing a kicker is an idiotic way to proceed. The better approach would be to fix the main motor in the first place.
We have kickers in the event of an unforeseen emergency, not to take care of foreseen problems due to our own negligence.
If your main motor has recurrent mechanical issues, installing a kicker is an idiotic way to proceed. The better approach would be to fix the main motor in the first place.
The issue is that down here all the *techies* are shade tree mechanics doing partial cures on very old motors, likes milking the owner repeatedly through the summer as knows that during the winter nobody goes boating. Club's boaters keeps askig me who's your mechanic when seeing and hearing my motors working as swiss clocks LOL!! It's the same issue that happens with most ladies going to the mechanic for car service..
The issue is that down here all the *techies* are shade tree mechanics doing partial cures on very old motors, likes milking the owner repeatedly through the summer as knows that during the winter nobody goes boating. Club's boaters keeps askig me who's your mechanic when seeing and hearing my motors working as swiss clocks LOL!! It's the same issue that happens with most ladies going to the mechanic for car service..
Awesome reply and it really hit home. I have an awesome mechanic and he has never led me astray. When I was working out of town on a long assignment and the wife had a problem with the car I always told her to go to John's. They knew me and her as well. They always fixed up her car with no hassle and no "ladies" issue. Because they knew when I finally got home and it was an issue I would raise holly heck.
Just had both cars serviced yesterday. Been with them for 25 years. The service manager is actually a LADY.
