I say that because I have to. I mean I do love it... though I was going to trade up to a 25 except the weight made me nervous that I'd sink my boat. The Battle Skiff has a short transom and the current breed of 4 strokes weigh A LOT.
My hull is rated for a 30 hp tiller but the Coast Guard required weight limit sticker (that they stuck to the inside of the transom and then fired 4 rivets through to make it either, A. look official, or B. conform to some insane law that requires a boat's weight limits to be permanently affixed to the hull and if it's a sticker please rivet the corners anyway....uh, what?), says that I probably shouldn't hang a 4 stroke 25 on the boat. Point being that a new 25 hp is 155- 190 lbs and I am already dancing the freeboard waltz.
What I am getting at is that "Can" and "May" mean totally different things. Basically, I "may" put a 30 hp motor on my boat but I "cannot".
So then what?
In order to run in skinny water I made a transom riser. I could have just bought a jack plate except for two reasons.
1. In an effort to keep this thing as light as possible, I don't have a battery to run the hydraulics of the jackplate on my boat
2. Just about every Jackplate has an "offset" that places the motor further away from the transom in order to give the prop better water to grip. The offset means that the boat would be too long and thus, I can't close my garage door.... ergo, my boat might be get stolen...sheeesh.
I was going to have this "Riser" built, but finally decide to just do it myself. The finished riser is two plates of 1/4" 6061 T6 Aluminum plate sandwiching some UHMW. With a little work I found a local supplier for plate aluminum. Another stop at my friendly neighborhood plastic shop and the hardware store for some stainless steel bolts, nuts and washers and away I went.
I originally shot for a 3" rise, thinking that it would be too much but knowing it would be relatively easy to cut more off than to sell myself short on the front side. The 3" rise turned out to be a little too much. I was grabbing air at Wide Open Throttle (WOT). Before I chopped it down, I added an SE Sport 200 Hydrofoil. A Whale Tail is what the dissenters call it. I chose not to bolt through the Anti-Ventilation plate and buy the "Sport Clip" which allows you to affix the foil without drilling through the motor...
My results are thus...
With the hydrofoil the the hole-shot (time to get the boat on plane) was reduced but so was top end speed. Plus the deal breaker was that the bolt-on sport clip pushed a pile of water and I wasn't cool with that. I unbolted it and and decided to knock an inch off.
Meanwhile, $12.95 from Amazon got me a cheap tachometer that told me if I was running in the optimal RPM range. From everything I could read on the matter the goal is to balance, hole shot, with top end speed and make sure that you are running your RPMs in the upper end of the suggested zone. My motor called for 5000-6000 RPMs at WOT.
With the whale tail removed and the riser chopped down 3/4" to put the motor 2 1/4" higher than stock, I was hitting 5600 RPM's and a top speed of 25 MPH.
The only thing left to consider was the prop. Every forum I read online kept suggesting that a dialed in prop was critical, and they all suggested the same guy to get the job done. I assembled my data and shot an email off to Ken at Propgods.com. The next morning my inbox held the detailed answer from Ken, who not only responded promptly and thoroughly, but did it even though he didn't actually sell the prop that I needed.
Following his advice I ordered a 9 1/4 x 10 cupped prop and waited.
When the box arrived, I swapped out the prop, trailered to the river, dropped the boat in, fired up the 15 and found improved hole shot, top end still at 25 mph and a RPMs at 5820.
When I got home I took out my drill, fired two new holes on the transom and bolted the 15 in place.
Dialed in.
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