Boat Unable to Plane Under Load

[seimm]

I recently bought a '94 Tracker Deep-V 17' alum. boat (weighs about 1000 lbs) with a mercury 40hp motor. The boat was checked by a mechanic and all was fine. When I take the boat out with a large load (3-4)people and gear it will not plane and only travels at 5-10 mph. If I take it out alone it does fine 25 - 30 mph (but a little slow to plane). A firend suggested a different propellar. The prop shop suggested a larger engine. This engine is the standard with this boat and Tracker Marine sells alot of these boats. I don't think I need a bigger motor but rather this motor may have problems. Under load it will not exceed 3000 rpms, but when not in gear it will rev. up to over 5000 rpms. Any ideas? and does it harm the motor when I take a heavy load out and run all day at 5-10 mph? Thanks for your assistance!

 

[Kiwi]

Re: Boat Unable to Plane Under Load

What size pitch is the prop you have on at the moment ? You must have a rev counter if you say it will rev up to over 5000rpm out of the water (which is NOT a good idea !) What are the max rev's that you get when you are in the boat alone at full throttle ? I would say you have the wrong prop on. Don't run your motor at full throttle if you are only getting 5-10 mph - you are putting severe strain on it. Lets know the answers to the above questions and we can help further. For now we will assume that the compressions on your engine are ok if you had a mechanic look at it.

 

[JB]

Re: Boat Unable to Plane Under Load

Ahoy, Basser. I'm with your prop shop. BPS offers Trackers as bare-bones cheap boats with the cheapest (read: smallest) engine they can find that will plane it with a 120# teenager and one gallon of fuel (exaggeration for impact). They overdid it with the Deep Vee 17 and now offer a 50 as standard on that boat. I think it is rated for 90 to 100hp. Check the ratings plate attached to the hull somewhere. My 950 pound Whaler 17 is rated for 100hp.<br /><br />The minimum hp needed to perform well at full load (listed on the rate plate) should be about 70% of the rated hp. Half the rated hp should do well with light loads. I suspect that you have less than half of the rated hp.<br /><br />Red sky at night. . .<br />JB

 

[thosch]

Re: Boat Unable to Plane Under Load

I recently bought a used Tracker 17Fish deep-V, and it has a 90 on it. Based on how mine performs, I would say a 40 would be definitely undersized.

 

[seimm]

Re: Boat Unable to Plane Under Load

Thanks for the responses.<br />The boat is rated for a 90 hp max. The typical rpms when I am boating alone is around 4000 to 5000 (I've only been out once on it alone, not real sure). I do not know the pitch for the prop, it is the standard prop for this motor. The prop shop mentioned that the pitch was 13 and I could try a 10, or vice versa, and they indicated that if I traveled alone I would have to switch back to the other pitch to avoid damaging the engine. It sounds like a new motor is the solution; would 60 hp be enough? As suggested by JB, this would be 70% of the max rated hp for this boat. I plan to often have up to 4 people on board. Also, I do recall the mechanic saying that the compression in one cylinder was 10 less than the other three, but he felt it was acceptable and should not cause a problem. This was over six months ago, I wonder if the compression could have gotten worse and maybe creating part of the problem, also this engine has not been tuned in several years, it ran smooth out of the water and thought I would wait until after this season to tune it. Thanks again for your assistance.

 

[JB]

Re: Boat Unable to Plane Under Load

I think a 60 would do well, Basser. A 70 would do even better than that if the budget permits. <br /><br />By the way, your engine has two cylinders. If one is down 10# to the other it is not a big deal as long as they both exceed 100#.<br /><br />Good luck and let us know what you do.<br /><br />Red sky at night. . .<br />JB

 

[my new fishmaster]

Re: Boat Unable to Plane Under Load

Hello fellow alum boat owner, I purchased a 96 Starcraft fishmaster 170 with a 75hp force i belive mine weights a little more around 1100. I had a 17pitch and could only go 15mph(3450rpms) then I droped down to a Hustler 13 wow (4300 rpms) 25mph. I have since returned the prop and droped down to a 11 pitch but have not tried it yet. I am guess I should get around 4700 rpms and gain 4 miles per hour