Weight Distribution - 17' Alumacraft Competitor - Tiller

[joeytmn]

I bought my first boat last September and I have a question about weight distribution. I was warned that it's a heavy boat by the seller, he called it a tank. In a good way. It's very sturdy in big water. So that's cool, but the first time I had a third adult hop in, the boat basically turned into a barge and just plowed water. With two "hefty" adults, gear and a cooler I have no complaints. It gets up on a plane no problem and scoots along just like you'd expect it to. Adding a third, non-hefty adult and gear was too much for it though. It couldn't get up on plane and the front end just plowed water. 

 

It has a 24v trolling motor on the bow. The two marine 12v batteries for the trolling motor are also in the front, not all the way in front, but close. A buddy said he'd try moving the batteries to the rear. So what I'm wondering is, how much weight can you put in the rear of these boats and is this a good idea? Assuming they'd even physically fit. The main battery is already in the rear. 

 

As a comparison, I have a 17' with a 60 HP 2 stroke and my dad has a 16' with a 50 HP 4 stroke, both tillers. My dad's boat slows down a bit with all of us in it, but easily gets up on plane and operates normally. His boat is a little more on the bare bones side and his motor is a good 10 years newer, but otherwise it's basically the same setup, but smaller, and it moves all of us around very well. This makes me wonder if my boat is or should be capable of more. 

 

I also thought of the possibility that my old 1997 2 stroke is just tired (is that a thing?), but it seems to run very well. I also took it to what I think is a good repair shop and they assured me that I have the correct prop. 

 

Here's all the info I can think of and a few pics.

 

1996 Alumacraft Competitor 170

1997 Mercury 60 HP 2 Stroke (60 HP is the max HP rating)

85" Beam (or close to that, can't remember for sure)

 

Try moving the batteries? Save up for a new motor? Or that's just the way it's going to be? Any advice from the community would be very much appreciated!

 

[delcecchi]

That is a lot of boat for a 60 hp motor, esp when loaded with 700 pounds of beef...  

 

Another possibility, since the boat is new to you, is that the foam flotation has gotten water logged over the years.   

 

It might be interesting to take the boat on the trailer and get it weighed someplace.    Compare the result to a calculated weight for boat motor trailer gas batteries etc.   

 

Or maybe remove a panel in the floor and see if the foam is wet.     A few hundred pounds of water (I found one account where the guy weighed the soggy foam he removed and got 525 pounds) would make a big difference.   

 

[leech~~]

Have you tried working with the tilt a bit like having it most the way or all the way down when taking off with a heavy load, then trimming it up more once on plane?  Even though you have the right prop there are other pitches you can buy for a better hole shot. 

My 17' Starcraft with a wheel and windshield is rated for 125hp but pops right up even with 4-5 people in it with a 75hp Merc on it. 

 

You might even try the ugly bolt-on trim tail on the motor.

Edited March 26, 2019 by leech~~

[bobbymalone]

Yeah, that kinda seems like what it should do with a 60hp motor.  What's a hefty dude?  Like 3 bills?

 

I'm kind of surprised a 60 is the max for the boat.  My 82 alumacraft is rated for a 60, same length but my beam is probably a foot and a half less.

Edited March 26, 2019 by bobbymalone

[BIGFISH.JZ]

That is a heavy trolling motor and 2 batteries aren't light either. As much as I would love to blame your merc for your experience, I'd have to say that the amount of weight in the boat is too much for maximum performance. I bet you're over the max weight. 

 But a couple things to check.... Compression/leakdown- will tell you if its "just tired". Spark plugs- cheap for that motor and notorious for fouling replace when checking compression. Coils are another common issue I see with that motor, confirm spark on all 3. Fuel hose- soft grey merc hose should be replaced. Fuel filters- often overlooked maintenance. Prop- if you don't have a spare, you could try going to a lower pitch. From 15 to 13 or 13 to 11. You should have a spare anyways. 

As mentioned above water absorption in foam and/or plywood adds considerable amount of weight. You can just elevate the bow and put a small bucket under the bilge plug hole. A "soaked" boat will slowly continue to drip for days. Dry boats stop dripping in minutes.

A brand new $90,000 Ranger would get you where you wanted to go, and with plenty of time for fishing!

[Surface Tension]

 Is the 3rd person sitting in the bow, if so move them back and how about the extra gear, can you move that back.

Are your trimming out when trying to get on plane?

What are your RPMS at WOT with 2 people? That leads into prop selection. 

[BobT]

I agree with Surface Tension. Weight distribution should typically be leaning toward the rear and prop selection could also be part of the problem. I'm assuming with the 60hp you have power trim? Perhaps the motor is trimmed down too low forcing the bow down too much. 

Edited March 27, 2019 by BobT

[leech~~]

I agree with Leech and Surface Tension on the prop pitch and trim thoughts.  Oh wait.   

[BIGFISH.JZ]

Let's just say that your mercury is 100% perfect(rare). On the topic of weight distribution only, the 150 lbs. You have at the bow is affecting the boat like it was 1000+ lbs at the stern. IMO the only chance you have of getting on plane with 3 guys, is to leave the troller and batts. on the dock. I have a 14' jon boat with 35hp that is a rocket ship with myself in it and still planes out with 3 guys. When I put a 12v Minn Kota maxxum on it, it wouldn't plane out at all!! 

[SkunkedAgain]

When my buddy Fat Pat sits in the bow of my boat (where you're not supposed to be when the boat is moving due to visibility), my 90hp is sluggish getting on plane - usually with one or two other guys in the middle with me. If I switch to my other prop with better hole shot, it pops out of the water. With Fat Pat back towards me it does just fine with either prop.