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Colby

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I searched for a thread such as this and couldn't find anything. On various forums I see the same questions over and over, "How fast will/should my *insert boat manufacturer name here* go with a *insert horsepower and outboard name here*? I have often thought the same. Hopefully this thread can cut down on some of those questions. Now, I know that speeds will vary by weight and modifications, so just give a short description of the boat. Maybe this could be a sticky. I'll go first..

'98 1648 Lowe Mod-V, '98 Johnson 48 SPL with a hydrofoil, 6 gallons of gas, 2 batteries, and myself (175 lbs) on glassy water topped out at around 37 MPH by GPS
 
I just bought a 1648 semi-V flat bottom Jon yesterday.
The guy that I bought it from tours the bass tournament trails in Florida.
It has all the bells and whistles of a great tournament bass boat.

Took it out for half a day today and it has SEVERAL issues to deal with.
#1 is the Humminbird transducer sprays water up over the motor.
Just found how to fix that here on this site.
#2 the hull leaks maybe 2 gallons and hour..... will fill the boat with water
tomorrow and see where that is happening - and fix it.
#3 it has a 35hp Force that pushes the boat 18-20mph and just seems a little
slow for a flat bottom.
Or, is that about par for a fully outfitted 1648 with a 35 ????
 

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Barefoot_Johnny said:
I just bought a 1648 semi-V flat bottom Jon yesterday.
The guy that I bought it from tours the bass tournament trails in Florida.
It has all the bells and whistles of a great tournament bass boat.

Took it out for half a day today and it has SEVERAL issues to deal with.
#1 is the Humminbird transducer sprays water up over the motor.
Just found how to fix that here on this site.
#2 the hull leaks maybe 2 gallons and hour..... will fill the boat with water
tomorrow and see where that is happening - and fix it.
#3 it has a 35hp Force that pushes the boat 18-20mph and just seems a little
slow for a flat bottom.
Or, is that about par for a fully outfitted 1648 with a 35 ????


I would have thought closer to 30 mph would be closer to par; but I don't know that hull. Hull shapes plays a big role.
Mine is a War Eagle 548LDV, Yamaha 4 stroke 25 (2000 model), I'm 190 lbs, with cooler full of ice and 10 average side rainbow trout, trolling motor on the front, one battery, 3 gal of gas, 7 fishing poles and a tackle box that weighs about 40 lbs, right at 29 mph. 9 7/8x11 1/4" OE Yamaha prop. Lightly loaded, with a turbo 10x11" SS 3 blade prop, upper 30mph range/ very low 31 mph, hitting the 6300 RPM limiter. Could be faster but I'm not racing anyone. Spend 90% of time idling.
 
Fisher sv-2 1989 vee, 76 inches wide at gunnel, 1988 johnson 48hp SPL, 6 gal gas, 2 batteries, another 700 lbs in gear and people, 30mph according to GPS.

Additional question to the tinboat community.
Will a flat bottom run faster (top end) than a rounded bottom boat? Assuming everything else is the same.

Tim
 
with all things being equal ,I'm of the opinion that a rounded hull will be faster that a flat bottom . I have no hard scientific evidence to back up that statement,just a gut feeling and a bit of experience :D

The 16' Lowe semi-V with abooout 450 lbs of persons and gear, 1995 25hp Evinrude built out of spare parts with a well worn 10 X 13 prop will do a solid 30 mph
 
Here are a boat speed and prop slip calculator if anyone is interested:

Theoretical Hull Speed = ( Prop Pitch X RPM ) / ( LU Gear Ratio X Constant of 1056 )

Prop Slip = ( Theo. Speed - Actual Speed ) / ( Theo. Speed )

I have found the speed one pretty accurate with small open v-hull skiffs. But where a lot of your guys' boats have extensive flooring, decking, and compartments ... I'd expect lower actual speeds due to weight carried. Also note a jon boat will have more wetted surface on the running hull and will be slower.
 
2014 Alumacraft with a 1956 Johnson Seahorse 15HP tiller handle, myself 195lbs with a little bit of gear, 20.6MPH on glassy water. Pretty dang good for a motor that old!
 
There's an app for that.. 8)

Back before smart phones I used my GPS and found out my old 15' modified Vee with a 15hp Evinrude did 21mph upstream and 23mph downstream on a local river.

And now, smart phone and the SpeedHUD app..

I'm looking forward to seeing what my new (to me) 14' MirroCraft and 15hp Yamaha will do.. I even have 3 and 4 blade props to compare. :D

Of course that's not going to happen on my local water.. It's currently got a surface so hard that you don't have to be Jesus to walk across it. Supposed to be -7F when I wake in the morning, and all the way up to 0F by noon!!
 
This is partially a cross-post so forgive the repeated language...

2010 Smokercraft Alaskan 15ft with 2010 20hp Yamaha Four Stroke.
Standard prop.

Solo (w/ trolling motor/battery, fishing gear, and full tank of gas), I get 24mph WOT when it is calm on the bayside. Can take a bit to get up on the plane with all the weight up the back, so I typically add a cinder block or two next to the battery in a box up front.

Two people in the boat w/ previously mentioned gear I will get around 22-24mph WOT. This is the ideal set-up for the boat and plenty of room for both to fish comfortably.

Three people in the boat (me at 330lbs) and two other both around 180lbs each the boat will get 18mph at WOT. It can be tough to get on the plane with three folks in the boat but is comfortable enough and still feels safe inshore.

We've added a fourth member a time or two when my other brother in law is in town but that is well above the max load capacity... while the boat still floats, she barely moves at about 8mph. Recommended only for short distances and with folks who are highly familiar with one another :)

Cheers,

Craig
 

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