plane question??

[jjk8]

I've recently picked up a 92 ProCraft 180 Dual Pro w/ 150 mariner Mag III(Bass boat). Took the boat out yesterday to the lake for the first time. I was given a few different props with the boat. The prop that was on it is a Mercury Trophy 13.75" 21p. The lake I went to is about 5,000' in elevation. My question is, what should I expect to be a normal time for the boat to plane? With the prop mentioned above it took about 7 secs with 3 adults in the boat. I put the other prop on, I'm not sure the size ( High Five), and it shaved about 1.5 seconds off. It also has a hydrolic jack lift on it too. I had the jack all the way down w/ trim all the way down out of the hole, after the boat would plane, I trimmed up but left the jack down. I reached around 5,000 rpms, but never topped out to the wot rpm's of 5600. The other question is for the few occasional times my kids might want to go out, do you think this setup will pull a tube around. This is my first boat. Thanks is advance for your input....

 

[Silvertip]

Re: plane question??

I'll answer you last question first. Yes it will pull a tube.
Determining the best prop is a compromise between hole shot and top speed which is why a jack plate was installed on the boat. Basically the jack plate allows raising and lowering the engine height. The fastest speed will be achieved with the jack plate raised to the point where the engine is at max RPM and raising any higher reduces speed or causes blow out (prop loses bite and over revs). One must also be careful not to raise the jackplate so high that the water pickup loses access to water so a water pressure gauge is very helpful. With the jack plate all the way down there is too much of the lower unit in the water so there is a great deal of resistance and performance suffers. The jack plate allows you to optimize setup for any prop. A prop with less pitch will give you better hole shot but may slow you down on top end. More pitch has the opposite effect. Hole shot and top speed with one style prop is a compromise but through careful selection you can find one that satisfies both needs, even if one or the other is not maximized. If you are pulling a tube say 50% and running faster the other 50% you may want two props. One for power, and one for speed.

 

[LubeDude]

Re: plane question??

Use the high five for pulling tubes and such, You will find the sweet spot eventually by trial and error. Try different hight of the jackplate for hole shots. You will get closer to your WOT RPM as you raise the jackplate after getting on plane. Your fastest prop will probably be the trophy. If your hole shot is still not satisfactory, see if you can put Smart Tabs on your application. Unbelieveable difference.

 

[jjk8]

Re: plane question??

Thanks for the above replies. I'm curious, does the time frame I described for the boat to plane seem ok?

 

[Frugal Floater]

Re: plane question??

Two links containing calculators that may help...not sure how accurate:

http://continuouswave.com/cgi-bin/propcalc.pl/
http://continuouswave.com/cgi-bin/crouchcalc.pl

 

[roscoe]

Re: plane question??

yes

 

[bassboy1]

Re: plane question??

What is the big thing with hole shot? If it takes 5 seconds or 8 seconds, what does it matter? How much is that 3 seconds gonna affect your life? I can see top speed being useful on long runs, but aside from pulling novice skiers I see no need for hole shot.

 

[jjk8]

Re: plane question??

What is the big thing with hole shot? If it takes 5 seconds or 8 seconds, what does it matter? How much is that 3 seconds gonna affect your life? I can see top speed being useful on long runs, but aside from pulling novice skiers I see no need for hole shot.

You are right, but regardless my question was whether it was reasonable or normal being as I am new to boating and am not experienced as to what should be expected. But thanks for your useful comments that I probably wouldn't have figured out otherwise?????????

 

[Silvertip]

Re: plane question??

Hole shot is one measure of boat set up. If a boat struggles to get on plane, that's not good for the engine and means the setup is wrong even if it does seem to run ok once it does get on plane. Top speed is just that. Its whatever speed you obtain when the setup allows the engine to operate at its maximum recommended wide open throttle RPM. More than that it's over reving. Less than that it's lugging. Therefore, hole shot and top speed are a compromise but you can tweak a little at either end to suit your fancy. If boats had transmissions you could have the best of both.