Prop question

[krispcritter]

I have a 2021 Suzuki DF30ATHL3 tiller steer motor on my 16-foot, 1988 Grumman Fisherman boat. Basically, a big heavy rowboat. My batteries are mounted midship, with the gas tank in the rear with me (6 gal). Even with my wife sitting at the bow, the boat does not want to plane like I think it should. Riding bow high even with trim maxed out. I added a small hydrofoil on the cav plate and that helped a little. I plan on moving the batteries further forward to reduce the weight at the stern.

The stock prop is a 3x10.25x12. Would a 4 blade prop help or should I consider a different pitch prop.  What say ye.

[lowaccord66]

Any idea what rpm range you are getting to at the top? 

[Badbrad2186]

I have a 2021 Suzuki DF30ATHL3 tiller steer motor on my 16-foot, 1988 Grumman Fisherman boat. Basically, a big heavy rowboat. My batteries are mounted midship, with the gas tank in the rear with me (6 gal). Even with my wife sitting at the bow, the boat does not want to plane like I think it should. Riding bow high even with trim maxed out. I added a small hydrofoil on the cav plate and that helped a little. I plan on moving the batteries further forward to reduce the weight at the stern.

The stock prop is a 3x10.25x12. Would a 4 blade prop help or should I consider a different pitch prop.  What say ye.

I had the same issue with a very similar boat moved the gas tank to the front of the boat and fixed the problem. Each gallon of gas weights around 6 lbs. 10 gallon tank is 60osh lbs

[Mac Attack]

I know you don’t want to hear this, but 30hp isn’t enough for that boat.
My BIL had. 16’ Sylvan with a 40hp Merc 2st and he could never get it to plane either.  I told him this as I had a 16’ Sylvan with a 55hp and it wouldn’t plane if I had more than 2 or 3 people on board.  Following year he sold the boat.  lol

A 4 blade prop will give you more “pop” out of the hole, but you lose top end because of drag.

I had a 16’ MirroCraft with a 40hp Yamaha 4st.  I moved the battery and fuel tank up front and it would plane.  However, I’m a fat a$$.

Good luck.

[krispcritter]

The boat specs say 35 HP max so it's not a Horsepower issue.  It originally had a 1986 Johnson 20 HP and it planed fine. I sucked weeds into the water intake and caused a thermal nuclear melt down of that motor.  Wife hated that motor as it was temperamental and being a 2 stroke, the exhaust made her sick. so, after the melt down I replaced with the larger 4 stroke. Significant weight increase on the new motor so I'm leaning towards the weight distribution being the issue.

The specs on new motor say 5600 to 6300 RPM at WOT. I don't know the actual RMP's I'm turning as I don't have a tach, just the idiot light on the motor.

I think I will move everything I can forward and see what that does.  This will be the easiest and cheapest option. If that does not work, I will readdress the issue.

Thank you for the input gents.

[fish/hunt4ever]

I 2nd the move of the gas tank forward. I had a 16 foot sylvan sea monster and it would not place with the 45 hp motor when the gas tank was in the rear, moved it under the console and batteries for the bow mount foward and it would do great with 3 or 4 people in the boat. It always amazed me with how the weight distribution helped out with any of the boats I have had.

[Jethro]

The boat specs say 35 HP max so it's not a Horsepower issue.  It originally had a 1986 Johnson 20 HP and it planed fine. I sucked weeds into the water intake and caused a thermal nuclear melt down of that motor.  Wife hated that motor as it was temperamental and being a 2 stroke, the exhaust made her sick. so, after the melt down I replaced with the larger 4 stroke. Significant weight increase on the new motor so I'm leaning towards the weight distribution being the issue.

The specs on new motor say 5600 to 6300 RPM at WOT. I don't know the actual RMP's I'm turning as I don't have a tach, just the idiot light on the motor.

I think I will move everything I can forward and see what that does.  This will be the easiest and cheapest option. If that does not work, I will readdress the issue.

Thank you for the input gents.

My 14' Starcraft Superfisherman is carrying a 25hp and rated to 30, so it might be a similar comparison to your boat. I can't run my boat without a hydrofoil. With just me it will eventually plane and really haul, but with 2 people, no matter where they sit the boat will take minutes to plane if it ever can. With the 'foil it pops right up on plane with 2 people but it unfortunately robs quite a few MPH off the top end. It's a worthwhile sacrifice.

I always meant to get a tiny-tach, they aren't much money and will tell you if you are turning the right RPM's.