New boat performance

New member here.

I just purchased a 1548 Alweld flat bottom boat (LA package), and I got a 20hp efi tohatsu to power it.
The hull weighs around 350lbs, and the motor, gas, and battery weigh roughly 170lbs. I’m about 200lbs. What kind of performance do y’all think I can expect with this setup? I’m going to be using it to duck hunt mostly, and will rarely put over 2 people in the boat.

Thanks for the input!

Txtincan said:

New member here.

I just purchased a 1548 Alweld flat bottom boat (LA package), and I got a 20hp efi tohatsu to power it.
The hull weighs around 350lbs, and the motor, gas, and battery weigh roughly 170lbs. I’m about 200lbs. What kind of performance do y’all think I can expect with this setup? I’m going to be using it to duck hunt mostly, and will rarely put over 2 people in the boat.

Thanks for the input!

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I got a 1448 grizz with a 20 Tohatsu. Im pushing 1000lbs. Getting 23mph @6100 with a 10 pitch prop. Was getting 25-26 with a 11.5.
Cheers

I have a 1448 with a 20 hp Yamaha, it came with a 12" pitch and with only me in the boat and basically nothing else it topped out at 27 mph. I usually have a lot of stuff even by myself in fishing gear and so it dropped in speed some about 4 mph. I sometimes fish with a friend of mine and with him and all our fishing gear the boat only does about 17 mph and sucks fuel. I need to use a different prop when I take him but, haven't gotten one yet. I am going to get a 10" pitch when I take him fishing. That won't improve top end much but should help fuel economy a lot.

So I took the boat out this morning for a few hours to start breaking the motor in. My total load was about 730lbs, but my typical load will either be about 800 lbs, or 1000 lbs depending if I have another person hunting with me. I was able to get 26mph when running at about 80-85% throttle. When I tried giving it more gas, the alarm indicator light came on, and the engine sounded a little off. It went away as soon as I backed off the throttle.

I’m thinking that I was hitting the rev limiter? I’m running a 10 pitch prop, but I don’t have a tachometer. I’m not sure if I should bight the bullet on a tach, or just go ahead and purchase an 11 pitch prop. What do y’all think?

Thanks!

Txtincan said:

So I took the boat out this morning for a few hours to start breaking the motor in. My total load was about 730lbs, but my typical load will either be about 800 lbs, or 1000 lbs depending if I have another person hunting with me. I was able to get 26mph when running at about 80-85% throttle. When I tried giving it more gas, the alarm indicator light came on, and the engine sounded a little off. It went away as soon as I backed off the throttle.

I’m thinking that I was hitting the rev limiter? I’m running a 10 pitch prop, but I don’t have a tachometer. I’m not sure if I should bight the bullet on a tach, or just go ahead and purchase an 11 pitch prop. What do y’all think?

Thanks!

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Did your 10 pitch come with the engine. Factory new comes with the 11.5.
You were probably hitting the rev limiter. My engine feels like its not working as hard with my 10 pitch and if I leave wot sustained sometimes it shows 6150-6200 and I get the rev limiter. I just back off a little but I don't do wot much. Get a 'tiny tac'. They're like 50.00 and very easy to attach to your plug wires. Not going back to my 11.5 prop.

Went and double checked the pitch, it’s definitely a 10. Just got off the phone with the dealer, they are going to swap the 10 for an 11.5! I described the symptoms and they recommended the 11.5 so for now I’ll try this before I have to spend any money.

Txtincan said:

Went and double checked the pitch, it’s definitely a 10. Just got off the phone with the dealer, they are going to swap the 10 for an 11.5! I described the symptoms and they recommended the 11.5 so for now I’ll try this before I have to spend any money.

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No matter what prop you use its still good to know what your engines rpm's are up to.

Good luck and welcome to the site.

If you plan on using the boat for duck hunting then you will be loading it up quite a bit. I would keep the 10 for those days and use the 11.5 for when it is just you fishing. Your fuel economy will show the difference. Too much pitch is overworking and lugging the motor and that is not good. IMO. Swapping out the prop is easy and takes maybe 5 minutes.

surfman said:

If you plan on using the boat for duck hunting then you will be loading it up quite a bit. I would keep the 10 for those days and use the 11.5 for when it is just you fishing. Your fuel economy will show the difference. Too much pitch is overworking and lugging the motor and that is not good. IMO. Swapping out the prop is easy and takes maybe 5 minutes.

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Have you tried your 10 pitch yet? What 1448 do you have. Reason I ask is my 1448 has a 17.5 transom. 15" shaft is actually 16".Tohatsu 20 manual says to mount the cav plate 1/4"-1" below the bottom of transom. I was getting spray back till I made a jackplate and lowered the engine. With the jack and 10 prop its running great. I still wonder why Tracker grizzly make a 17.5 transom. Too long for a short shaft and too short for a long shaft.

No, I haven't tried the 10" pitch yet, I haven't even bought it yet but am planning too. My 1448 has a 20" transom and a 20" motor, I have a home made bracket that sets the motor back about 3" not sure about my anti-cavitation plate but I have the motor mounted as high as possible, it will blow out in some conditions. I should measure that. I added float pods too and that helped a lot too. When I fish with my friend, we both weigh about 200 lbs and all our gear, the fuel economy on my boat goes way down. I will take some measurements of all. I just never have actually put a tape on any of it and people are always talking about an inch here and an inch there. I should know these things.

surfman said:

No, I haven't tried the 10" pitch yet, I haven't even bought it yet but am planning too. My 1448 has a 20" transom and a 20" motor, I have a home made bracket that sets the motor back about 3" not sure about my anti-cavitation plate but I have the motor mounted as high as possible, it will blow out in some conditions. I should measure that. I added float pods too and that helped a lot too. When I fish with my friend, we both weigh about 200 lbs and all our gear, the fuel economy on my boat goes way down. I will take some measurements of all. I just never have actually put a tape on any of it and people are always talking about an inch here and an inch there. I should know these things.

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After a bunch of trial and error my cav plate sits 1/2" above the bottom and 6" setback. Had to bring it back that far to clear the harness clamps and adj. screws. The 10" prop gives a better hole shot and the engine doesn't feel like its working as hard.

Cheers

Well I’m an idiot. I have been going on assumptions and my eye. Today I got out the tape measure and holy smokes was I way off. So I have a 20” transom and bought a 20” Yamaha. Turns out the transom tapes at 21” and the motor tapes from the bracket to the anti-ventilation plate at 22.5”. I built a bracket that has a 5.5” set back. Just judging from looking at the top I thought my motor was about an inch above the bottom of the boat. Then I laid out the straight edge and was I surprised. My motor is almost an inch and a half below the bottom of the boat! I have the motor on the top pin. It runs great and sometimes will suck a little air in rough water and loose it’s bite, I simply back off and it grabs and is good again.

So I want more. I went ahead and raised it another inch. No way on the top pin. Lowered to the next pin still won’t hold. Drop to the next pin, there are 4 pin holes. If I gas it hard it seems to work until I hit top end. If I take it easy it will hold even at WOT. But is defiantly on the edge. Lower to the bottom pin motor holds but it is definitely trimmed down too much. I don’t like it. Pictures show where it is now on second pin.

The problem could be exasperated by the skeg guard I have bolted on the motor. The guard didn’t slow it down any but now I’m thinking it is causing enough turbulence that it is inducing air. Maybe, not sure.

I am going to lower the motor 1/2” and try that. Every little bit helps.

Ditch the skeg guard and do your testing. That is a behemoth of a skeg guard in that it incorporates an afterplane as well. Not needed.
After doing your testing then try the guard again if you want and you will see why I say to ditch it!
If you insist on keeping the guard then you are too high at your present height. Cut the 1" you raised the engine down to 1/2" and see how it performs.
You can have cup added to the prop to keep it hooked up better when you are running higher on the transom.

Actually I did remove the skeg guard for the testing but, the angle brackets that bolt to the anti-ventilation plate were still attached. I can't ditch the skeg guard, I run my boat in a rocky area and that thing allows me to bounce over rocks all day with no worries.


It only lowered my top end by 1 mph but made the steering a little more reactive as you can imagine. I have no issues with porpoising or bow rise.

Ok, I actually ended up with a 12 pitch prop from the dealer, and took it out last week. Was able to take it out last week and my top end speed went up to 29 mph, however the boat didn’t jump up as quick. Tomorrow will be the first day with a realistic load in the boat ( an additional 250 lbs) . Hoping that I can at least cruise in the low 20s.

I'm guessing that you didn't get the alarm buzzer this time. I would hold onto the 10" pitch for days when you load up the boat and try that too.