Boat lifts up too high (needs front weights)

[mr_plow]

hi after a long time my ski boat is finally on the water. its a fibreglass skicraft hull (late 80's early 90's), paired with a mercury blackmax 135 v6 outboard and an 80 litre tank in mid bow.

i have found at low crusing speed and taking off the bow of the boat lifts way to high, its abit unsafe only being able to see tree tops and sky(also just looks plain stupid), then when speed is picked up the bow comes down to a good height. i got a buddy of mine to sit right on the end of the bow (he is about 80kg) and the boat sat alot better taking off and slow crusing.
i am guessing i need to stick some sort of weights at the bow (100kg or more). whats the best way to go about this? should i put a bunch of 20kg cement bags up the front or something like a ballast bag full of water? something else?

needs to be a quick fix as ive planned abit of water skiing next weekend.

thanks!

 

[Sabbath]

Re: Boat lifts up too high (needs front weights)

Look at Smart Tabs, they've been covered plenty on this forum.

 

[Philster]

Re: Boat lifts up too high (needs front weights)

You could, but carrying extra weight to fix another inherent issue isn't the best/safest option. Need questions answered first:

Does your motor have trim control?

Does your boat have trim tabs?

Is the motor too big for the boat? How big is the boat?

 

[bick]

Re: Boat lifts up too high (needs front weights)

This is what you need to look into... http://www.nauticusinc.com/index.html

 

[mr_plow]

Re: Boat lifts up too high (needs front weights)

You could, but carrying extra weight to fix another inherent issue isn't the best/safest option. Need questions answered first:

Does your motor have trim control?

Does your boat have trim tabs?

Is the motor too big for the boat? How big is the boat?

the motor has trim control (up & down), don't have trim tabs,

the motor is pretty big but i don't think its too large, the boat is a 5 seater, im pretty sure its 5.8 meters long.

also when sitting on the front of the boat it lifted the rear and made it sit alot better, just seems like there is too much weight on the rear and no enough on the front

 

[bayoucat58]

Re: Boat lifts up too high (needs front weights)

If your boat is between 15'-17' you are overpowered some with that heavy Max V-6. not to worry go to Lenco .com and check out there new line of trim tabs. I run them on my offshore fishing boat and my Shallow water 20' Glasstream that has a ton of power with the Yamaha 130....Good Luck and "Don't forget to bring a towel"

 

[sschefer]

Re: Boat lifts up too high (needs front weights)

I always see recommendations on how to fix it but I rarely see anyone explaining why it happens. Perhaps if you understood that, it would be easier to fix it.

When a planeing hull moves through the water at slow speeds it emulates the same features of a displacement hull in that it pushes water away from the hull. The bow wake is formed and rises up in front of the boat. In order to plane, the boat has to rise above the bow wake. When speed is increased in small increments the bow will climb the bow wake and the stern will drop when the balance of the boat is disrupted.

Smart Tabs and Engine Trim can be used to keep the stern from dropping. This effect lifts the entire boat since the bow is still trying to climb the bow wake. Too much stern lift and you'll drive the bow down into the bow wake and cause a unsafe conditiion. Not enough power and you won't create enough stern lift.

The first place to look for problems is in the engines ability to create stern lift on your boat. Almost any good boat building book will show examples of a boat with high bow or porposing problems. The cure is first, does the engine have enough power to lift the stern and hold the bow up, second is it prop'd correctly and third, the design of the hull requires trim tabs to assist planeing.

So, if you've thoroughly investigated engine hp vs. manufactures recommendation and prop size and have done all you can do in that arena, then start looking at tabs as a possible solution.

 

[Chris1956]

Re: Boat lifts up too high (needs front weights)

Make sure the motor is trimmed all the way down, when you start to plane. You can remove the tilt pin to allow it to trim down more. I have that motor on my 16 footer, w/o incident.

 

[mr_plow]

Re: Boat lifts up too high (needs front weights)

Make sure the motor is trimmed all the way down, when you start to plane. You can remove the tilt pin to allow it to trim down more. I have that motor on my 16 footer, w/o incident.

at planing speed the front comes down, its just the initial take off (slow and fast) and crusing slowly (20 knots and under)
i did find that when the tilt was up a little bit it reached for the sky, but all the way down it made alot of difference but still its not good, i noticed that the little trim tab thing above the prop has perished away abit, could a new one help my cause?
any other suggestions before i blow 200 bucks on trim tabs?
http://cgi.ebay.com.au/ws/eBayISAPI...sPageName=VIP:watchlink:top:en#ht_1068wt_1139

 

[Larry Tate]

Re: Boat lifts up too high (needs front weights)

trim tabs are a great luxury. for that price, brand new, you will be happy you did it once its all hooked up. if ur rig isn't running right, unfortunately, ur gonna have to spend some cash to get it done right (remember B.O.A.T) but you will be happy when u do

 

[spdracr39]

Re: Boat lifts up too high (needs front weights)

I had a boat with this issue and it turned out the floor and transom were water logged

 

[zopperman]

Re: Boat lifts up too high (needs front weights)

I had a boat with this issue and it turned out the floor and transom were water logged

I'd hope it's not a waterlogged hull since he said he finally got it on the water

Usually a hydrofoil or trim tabs (either smart of helm adjustable) can remedy bow rise.

 

[mr_plow]

Re: Boat lifts up too high (needs front weights)

I had a boat with this issue and it turned out the floor and transom were water logged

if it were water logged wouldn't it make water sloshing sounds on the trailer of just when being moved out of the water?

 

[jayhanig]

Re: Boat lifts up too high (needs front weights)

Look at Smart Tabs, they've been covered plenty on this forum.

Ditto.

 

[zopperman]

Re: Boat lifts up too high (needs front weights)

if it were water logged wouldn't it make water sloshing sounds on the trailer of just when being moved out of the water?

No. If the foam or wood has absorbed water, it will not slosh around. Think about a sponge, does it slosh around? I DOUBT this is the issue... unless this is a recent development and you've had the boat for a while.

 

[cyclops2]

Re: Boat lifts up too high (needs front weights)

Can you get the WIDTH of the hull at the water line?
My Chaparral is 18.5" long @ the WL. It is 7' 7" wide @ the water line. Has a 5 L I/O Chevy in it. It climbs up a angle of at least 30 degrees with 1 or 2 people. Trim in or out makes little difference.
Full power shortens that stupid looking bow in the sky look.

I will have the inner hull area checked for gasoline & or water being absorbed, next spring.

Good post problem for older boats. Thanks.

 

[Chinewalker]

Re: Boat lifts up too high (needs front weights)

Is the boat unstable or otherwise dangerous when coming up on plane? If not, I'd just make it a point to take a good look around you for traffic, jab the throttle and get 'er up on step. Most you should be missing the view is a couple-three seconds or so with that V6. If someone is close enough that they would become an issue in that span, then they're too close to begin with...

 

[Texasmark]

Re: Boat lifts up too high (needs front weights)

i always see recommendations on how to fix it but i rarely see anyone explaining why it happens. Perhaps if you understood that, it would be easier to fix it.

ditto.