What do you think, too big or just right?

[SmallNFast]

We bought a small 13' Mini-Hawk earlier this year with a 25 horse motor. It does about 30 with one person, and around 25 with two people.

We decided that, rather than run it close to full throttle all the time, we would buy a used engine for it. We were looking for something like 35 horse, MAYBE 40, but my dad talked to a dealer we bought our Moomba XLV Wakeboarding boat form and the guy told us he'd sell us a 45 horse with controls for $500.

We know the guy, and know he's not out to screw us over, so of course we bought it. My question is though...is this too big? the 45 horse weighs the same as a 40, just bored out a little bigger, and weighs in at about 180 lbs. The motor we took off is a little under 120. We're putting some ballast in the front of the boat, but it really is a SMALL boat. 13' and probably has a beam of a little over 3'. We wanted more speed, but we're a little worried about what could happen. We're thinking like 50-55 mph, as the bottom of the boat is real flat and doesn't drag much. It has a V-hull but it's VERY small, and even at planing speeds only the back of the boat is really in the water. We have trim tabs on it, so those should help. It's getting taken out this weekend, and I'm just curious what you guys think about it?

Would post a picture of the boat with the new engine, but it's in the garage right now, not much room to take a picture. The 45 horse is about 6 inches taller at the top due to the added 2 cylinders, and about 4 inches longer at the shaft.

(woohoo first post, nice to be here )

 

[Mark42]

Re: What do you think, too big or just right?

I suspect you will exceede 40mph. The heavier engine may cause the boat to sit lower in the stern and allow water to splash over the transom. Get a bilge pump.

BTW, twice the horsepower generally does not double the speed. But you will use more gas.

 

[MikDee]

Re: What do you think, too big or just right?

I knew a guy that used to sell them when they first came out, his was black with a teal, mauve, and blue, color scheme, really sharp! And he had a 70 Tohatsu motor on it, I thought he was crazy! but he had it a few years, used in the Great South Bay, Long Island, and lived through it,,, lol

 

[SmallNFast]

Re: What do you think, too big or just right?

We've got a bilge pump, and we know it works

I know that twice the horsepower doesn't double the speed, but once we put a different prop on it we should get 50+. We don't need the acceleration out of the hole to come from the prop, we know that we've got plenty of power with the motor. We'll definitely keep it a three-blade prop and we'll play around with a few different pitches.

Yeah, I'm not all that fond of my paint scheme, some guy that paints cars got bored and did it. It'll probably be repainted by us over the winter, the paints cracked around all the cleats, the horn, the gas cap etc. And it bubbles on the sides below the waterline. Needs some work, but I'm willing to put the time into it.

I seriously can't wait to see how it goes
We have a place on a small lake in Weare, NH, lake is about 2 miles long, and a mile and a half wide at the widest point. Only half the lake has houses on it (one whole side is owned by a judge that won't sell any of the land...thankfully).
I don't plan on going anywhere near full throttle unless it's very smooth...i'd rather NOT die

 

[EricR]

Re: What do you think, too big or just right?

I guess I need to ask what the hull is rated for?

 

[MikDee]

Re: What do you think, too big or just right?

The guy I mentioned was a private dealer, he showed me an advertising video of the boat when they first came out. I think they were made to hold up to a 45hp motor but won't swear to that, he told me his was a "special" model made for the 70hp motor, but knowing him, I wasn't sure it was true?

 

[SmallNFast]

Re: What do you think, too big or just right?

Heres we go with the new pic, in the water:

Looks a little big, but not ridiculous. We REALLY need a new prop for it, the prop thats on it is a 12 pitch, because the motor came off a pontoon boat. DAMN does it have some acceleration, but we only get a little over 35 mph out of her. Although, on the good side thats at about half throttle (can't go any higher because thats almost at redline).

My dads gonna look for a used 14 pitch, hopefully he'll find something soon.

On the bright side, when I turn this prop doesn't catch any air, so i can actually turn while running more than 10 mph


Oh yeah, the US Coast Guard rated the hull for a 20 hp engine...thats what the plate on the back of the boat said...(so we turned it over and screwed it back on...now it just looks faded...hehe)

 

[rndn]

Re: What do you think, too big or just right?

That must be a riot to take for a drive!!

 

[bassboy1]

Re: What do you think, too big or just right?

You say that the shaft was something like 4 inches longer? That is the reason you don't blow out on a turn, but also slowing you down. A jackplate may help ya. Personally, I would start checking out what the bass boat guys do to make their boat faster. Does this boat have a pad?

 

[studlymandingo]

Re: What do you think, too big or just right?

Bassboy is right, you need to get the setup just right to really make that little thing perform. The A/V plate should be slightly above the plane of the keel. If you are redlining at half-throttle with the 12 then you will want to go higher than a 14; from the sound of it, I would probably start with a 17p.

If that's where you are now, then you can probably get close to 50 once you are dialed-in with everything.​

 

[Wotam]

Re: What do you think, too big or just right?

Make sure you wear a PFD in that boat at all times. It wouldn't take much to upset the proverbial applecart at speed.

 

[SmallNFast]

Re: What do you think, too big or just right?

A 17 pitch would be way too excessive? We tried a 15 today and it's a little too much. We get ZERO acceleration with two people in the boat...literally takes like 25-30 seconds to plane.

I have to return it sometime before the weekend and we're gonna try a 14, see how that goes.

We've been having some problems with the motor though, it's only firing on 3 cylinders consistently. We got some new spark plugs because 2 of the old ones didn't look so nice (so we replaced all 4), but we think one of the plug wires is bad aswell. So my dad made his own and he said it seemed to run better. It just seems like every little thing we do makes it a LITTLE better, nothing actually fixes the problems. We basically spent all day today (tuesday) working on it. We've gotten the top speed a bit better, up to a little over 40...

We have a jackplate, we had to jack this motor up something like 3 and a half inches so it runs well. We also have some Smart Tabs that we put on a few weeks ago to try and get the boat out of the water a little more. What we really need though is power trim. If we put the motor up one notch it barely takes off with one person, so we're running with the motor straight up and down. We're looking for a power trim setup on craiglist and such for cheap...hoping to find something.

The difference in jacking the motor up is huge. From the first hole (we had 35) to the second we got like a 6-7 mph increase (41-42)theres like six notches to prop the motor up, so if we could get it to the same angle as like the 4th or 5th ones at high speeds i'm sure we could get 50+.

And I definitely wear a PFD any time I'm in the little girl, as well as the safety lanyard for shutoff. Little tipsy with that motor stickin up so far.

Thanks for the input guys!