please help with balancing a 14ft fibreglass speed/ski boat

hi, can anyone enlighten me on a few of the finer points on getting a boats balance correct, how to know when it is correct, and the way it performs when its all set up wrong?
I have a fully restored 1972 14 ft fibreglass ski/speed boat, its similar to the sidewinder and the glastron gt 150, perhaps it is even a clone..
generally speaking they are for river use, and the normal motor size is around 115 powerhead hp, transom is quite thick (2inches) and they are rated for 125hp, which i presume would mean powerhead rated not prop, i have a 130 prop rated on it...
I have fitted 4 knee braces tied into floor stringers, glassed into a steel reinforced mount that top motor mount bolts fit through, i have also tied top bolts into front of splashwell with threaded rod,and built up transom so either side of transom is much further from the water and sealed them up as ice and drink storage, the floor has just been replaced also and filled with expanding foam, after i gave the underfloor another fresh coat of resin, and glass where needed, then a coat of northane paint before sealing it all back up..
I felt the boat was a bit heavy at the back, so moved both batteries up very front then had 2 x 25l fuel tanks up front behind them, boat feels very heavy on the water, drafting deeper and became very uncomfortable when flying over the chop, so i then fitted suspension seat mounts which added further weight and have now realised that i need to sort it all out a bit better to hopefully get a lot better ride out of it...
So far i have just fitted a floatation pod on either side of transom, they are glassed on and combine to 40litres of water that will be displaced under waterline, does anyone have any constructive advice on where batteries and fuel tanks should be or how these pods should change the way the boat goes? do i want weight up very front or does this magnify the weight in some way compared to being midships or at rear? seating pos is 1/3 rd from front, i run in the ocean only, where it is usually quite choppy, so i want balance as best as i can get it, but have no idea where to start due to soo many variables, can anyone tell me what i need to aim for, do i want front heavy or rear, or put as much weight as close to middle as possible? i am well aware its only a small river boat, but it does handle ocean with ease, so no need reply with useless responses, if you cant help please just move on and dont waste anyones time by responding,

thankyou kindly...

A good starting point is to measure the full length of the boat right down the middle front to transom.
Now dive that by 3, so for example a 15ft boat is 3x5ft..
Now from the transom measure the 5ft and that is where the ideal balance point will be.
do this with everything you normally carry in the boat and put something roughly the same weight as you the driver, you can then shift stuff around to get
the balance point.
to do this the boat needs to be on the trailer and a simple bit of strong wood going from side to side and a couple of stands this can be done easy and quickly.
you dont need to jack it up sky high, just enough to clear the trailer bunks at this point. if you have long bunks it will be dead simple to do.
I have used an old scaffold pole with a bit of carpet so it dont scrat the underneath of the boat.
so thats your length sorted out.
now the easy bit bit, balance side to side ... for this its easier than you might think because you want the boat in the water to do this easy.
simple get someone of around similar weight to sit in the drivers seat and look at the back of the boat noting if one side is lower in the water.

This will not be 100% perfect for every boat, but about as close as you can get it without tons of testing at different speeds and is a good
starting point, especially if you want to go jumping waves etc.
But the balance goes right out the window when more passengers and goods are taken onto the boat. you might have to shift stuff around, but you will get
a good idea of the stationary attitude that the boat should be at.
I have seen so many boats almost nose dive when crossing wakes and or waves due to being too front heavy, that is dangerous.


hope this helps

p.s this is only for planning hulls.

Some of this can be in the prop as well. Bow vs. stern lift and prop slap/torque.

The 130 is fine but some prop rated are quite a bit heavier then 115 125 powerhead rated.

Without a pad the extra speed can ride higher on the keel that will give you the list to one side as theirs less to balance on, and to much bow lift will give you the porpoise effect.

Gas as in the front should probably stay.

What in paticular is causeinh the unesy feeling. Listing, bow angle, shuddering, porpoise, wobble ect.

I have a 72 CV16 Carlson...bathtub bottom ,no pad ...150 60 deg Johnson...4" setback jackplate...propshaft about 1" below keel..20 gal fuel tank against the transom in the center...battery just ahead of driver in the center...
This boat is very prone to bow steer...under acceleration with negative trim ,it dives to the right rub rail...with a bit too much positive trim it goes to the left rub rail...there is a small window of trim where it balances nicely , and that's where you run it...I've known the boat since it was bought new by a friend , and have owned it for decades... this is the set up I am happiest with after years of playing with it...
weight in the front adds to the bow steer problem....the motor too deep adds to the bow steer problem....
by it's design it's not a WOT speed boat...it was made for skiing with low hp motor....I run the V6 with a 19 " 4 blade so it will pull up a barefooter with no problem...let it bang the rev limiter up top...
Don't know if yours has this same bottom but that's where I'm at with mine....

hi, thanks for your reply, mostly it is just the hard hits when goin over swells and chop, at one point it just skimmed over the top of it all effortlessly, but i took that to just be how the boat went, and didnt write down how i had it all set up so have no idea how to get it back there again...

That Leeds me to. Not enough bow lift or heavy in front. Might put the battery back since adding the suspension seat.

Think of it like a lever. 10# 10’ in front of the water line equals 100# of force. It’s not the same as 100# in the bow but it can act like it under motion.

I'm still curious about the "Suspension seat mounts" in a 14' boat.

Saves the tailbone if your bouncing chop all day in.

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Originally Posted by home made tunnel

I'm still curious about the "Suspension seat mounts" in a 14' boat.

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He might need to change spring rate or shock oil ... :D

http://shockwaveseats.com/wp-content...-2-800x800.jpg
Don't forget :nonod: about the passengers ... :thumbsup:

http://shockwaveseats.com/wp-content...00-800x800.jpg

I mean - we're talking micro boats - My size - Boston Whaler size - Little Bitty Boats. Why a suspension seat?
I'm still curious to see this setup lol.

Quote:

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Originally Posted by home made tunnel

I mean - we're talking micro boats - My size - Boston Whaler size - Little Bitty Boats. Why a suspension seat?
I'm still curious to see this setup lol.

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Haha. Well I went out few days ago on one my bigger lakes and wind picked up gud and beat me to death and just wore my ass out!! Its 18.5ft which ain't big but rides pretty gud,, I wouldnt even attempted in my ole 15fter. He did say he always in ocean , I could c y , but I would like to see the set up

Quote:

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Originally Posted by home made tunnel

I mean - we're talking micro boats - My size - Boston Whaler size - Little Bitty Boats. Why a suspension seat?
I'm still curious to see this setup lol.

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Hey now Mr. HomeMade Kids .. err .. tunnel .. err .. congrats on the latest news !

ifin I gotta either get up and go look at the sharpie marks on the steerin arms @ 100+ to make sure everybody's lined up ... or switch over to yama-matic's ... :nonod: :nonod:

You will have to be open-minded enough to see the value of three of them Corbin Marine suspension seat's in sub 14' hulls .... :leaving:

Chaz = thinkin , that tryin to take an antique barrel bottom boat and treat is like it has a pad , some deadrise , and a few lifting strakes .. will soon be wet :rolleyes:

Being cool in old rallysport 16(sidewinder copy) I nailed it in 2-3 foot waves ran for a 15 minutes I was cool. Pulled into the ramp and could not bend over to hook the boat next morning couldn't pee bruised the prostrate. Barrel bottoms beat the crap out of you.

Quote:

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Originally Posted by home made tunnel

I mean - we're talking micro boats - My size - Boston Whaler size - Little Bitty Boats. Why a suspension seat?
I'm still curious to see this setup lol.

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