Some Questions regarding many things, plaining etc..

y2jericho

Petty Officer 2nd Class
Joined
Aug 30, 2002
Messages
146
Well i finally fixed up my motor with just the tilt and trim to complete but i decided to go on the water and it was a beautiful day. There was a bit of wind with maybe 1-2 foot swells on the water. I realised that the motor is sitting very low in the water on the back when the boat is standing like the motor is to heavy for my boat or something, though it is within regulations. I was thinking of putting some bar bells underneath the front bow to about 40kg and some lead to about 20 so 60kg. The motor is sitting so low that it is taking on water in the motor drail well but maybe like only 20ml but the drain well hole is sitting right above or in the water and it is worrying me.. It evened out when my dad sat at the front<br /><br />As an experiment i got my dad to sit on the bow when i was driving and for the first time i experienced "plaining" and was looking on the speedo and we were going at least 40 or so nautical miles after normally only experiencing 20 or so "cutting" through the water. But to experience the 40mph i had to go wide open...<br /><br />Also before when i had no weight on the front with it going at WOT i had 3500 or so RPM but when it started plaining i had at least 4300-4700 on the tacho WOT<br /><br />When is hits the ripples in the water is it normal for the boat to make loud noises like its hitting against a flat surface ebcause thats what it was doing ...<br /><br />Maybe i need a new propellar (i don't know what pitch i have currently but it seems like its very flat like its not cutting through the water but pushing it...<br /><br />The boat is a 4.33m Runabout and its fairly shallow but wide boat and it has a 65hp Mercury Thunderbolt motor. I always have a 4.5hp Mercury Kicker (brand new from shop maybe 10 hours but its 20 years old but honestly like new) Should i be going in a bay around 1-2km from the opening to the open ocean on pretty good to medium to normal breezish days or should i just stick to river etc.. If a swell hits us from side on the boat rocks and if you were standing you would easily fall out but it does not take on water from the sides but it looks like it nearly will.. <br /><br />This boat was absolutely flying on the water when my dad was sitting on the bow as the weigh was evened out and on WOT it got onto plain without a problem <br /><br />Anyway Have a good Australia Day Long Weekend you Ozzies out there. <br /><br />Beautiful 33c-40c wheather for last 2 and the next 5 days in Australia. And not to windy but with a nice cool breeze and heaps of bream ;)
 

JB

Honorary Moderator Emeritus
Joined
Mar 25, 2001
Messages
45,907
Re: Some Questions regarding many things, plaining etc..

G'Day, Jericho.<br /><br />Your boat is performing normally for a poorly balanced boat with too much prop.<br /><br />There may be other factors involved.<br /><br />If your stern sits that low, it may have too much weight aft. The engine is the main suspect, but other things could be the causes. Where is your battery? Your fuel tank? How far aft do you sit?<br /><br />Difficulty planing is likely to be a prop issue, as is the low rpm at WOT. You should reach 5500rpm or so at WOT. That suggests a prop with about 3" less pitch. Your accelleration will be much improved as well.<br /><br />You can also add a hydrofoil to help plane at lower speed and with less power.<br /><br />Good luck and let us know what you do. :)
 

River fish

Cadet
Joined
Jul 4, 2002
Messages
22
Re: Some Questions regarding many things, plaining etc..

Everything that JB says is correct, I had similar problems a couple of years ago on an old 15'tri-hull and was able to solve much of the planing and balance problems by moving the trolling battery and seating arrangements around.<br />I am however curious about the Kicker you mention, you might get rid of quite a bit of your stern to bow balance problem if you removed it and tried it with out it. if you just use the Kicker for fishing ( i.e. non trolling )you could also replace it with a bow mounted trolling motor to help re-distribute the weight balance if necessary, but I would try to approximate the new trolliing motor weight up front with a "test weight" first just to see how things go. good luck, Bruce
 

Solittle

Fleet Admiral
Joined
Apr 28, 2002
Messages
7,518
Re: Some Questions regarding many things, plaining etc..

Jericho - I wouldn't do a lot other than shifting wieght around until you get the trim/tilt working. Having control over the trim will greatly affect how the boat rides and handles.
 

y2jericho

Petty Officer 2nd Class
Joined
Aug 30, 2002
Messages
146
Re: Some Questions regarding many things, plaining etc..

trim/tilt works perfect but it leaks oil occasionally<br /><br />I have 30l tank and the battery at the back one on each side of the bilge... <br /><br />When i actually got it on plain i was getting 4000-4500 .. But when it was cutting through the water it stayed at 3500 if you know what i mean<br /><br />I had a hydro foil but i removed it then my mechanic dropped a spanner on the leg where the hydrofoil screws onto and snapped half of it off i still have to get it welded back on.. :( <br /><br />Only way i could get boat on plain was to get someone to sit on bow when driving. <br /><br />What pitch prop do you recommend for my boat? Also theres really no other place at all i can put my battery.. My backup motor is a 4.5hp kicker on the port side and it is really a "just incase" motor. Also i realised when my dad sat on the bow the boats motor raised up a bit.<br /><br />I wan't quick acceleration so i can pull a ski bob or skiier (doesn't have to be good just for fun.. Don't have money for a v8 boat :D ) And to get on plain quick under WOT so i can wave crash to my fishing area ;D<br /><br />Thanks
 

JB

Honorary Moderator Emeritus
Joined
Mar 25, 2001
Messages
45,907
Re: Some Questions regarding many things, plaining etc..

Hi, Jericho.<br /><br />Check the pitch on your prop. Get one with 3" less.
 
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