Center of gravity and weight

[SuzukiChopper]

This might be a little long winded so please bare with me.

I just got done cutting open the bow of my boat and hacked off most of the dash area. I love how it's looking so far and can't wait to start building my new vision. TONS more room. I know that because of the drawings I've done and the thinking I've been doing I'll be able to fly through this project IF it ever warms up enough (been -30c [-22f] here for a few weeks and now just warming up to about -17c [2f]) to stay in the garage long enough. I'm going to be adding a deck up front with a live well and hopefully 2 battery compartments (trolling motor). I'm going to be relocating the 19 gallon gas tank to just in front of the splashwell instead of in the bow. The starting battery will be located just in front of the transom as will my main storage areas.

My dilemma is this:

The black line shows approximately where it sits in the water when loaded (somewhere around the middle of the line). After looking at many many pictures of other v-hull boats mine seems to sit too high and too evenly distributed from bow to stern. It planes out very quickly and does need to be trimmed out quite a bit to get it to where it isn't scary. It's also subject to listing pretty good when just sitting in calm waters and someone moves. It's a 16' boat and I'd like to find the center of gravity so that I can balance it properly while I'm making my new mods. I have the means to lift it, just don't know where. I'd also like to know if it is sitting too high. years ago before I did the transom, stringers and deck... the water was about 1/2" above that last "chine". It sits about 4 1/2" higher in the water now. Any advice? Thanks!

 

[Dunaruna]

Re: Center of gravity and weight

Any idea what your deadrise is?

 

[SuzukiChopper]

Re: Center of gravity and weight

about 20 degrees.

 

[ondarvr]

Re: Center of gravity and weight

So what do you plan to do if it sits too high?

If it sat higher after you rebuilt it, either you changed what was there, or the old foam was waterlogged, if it was waterlogged then you returned it to where it would have been when new. Knowing the center of gravity will do you little good at this point, just put everything where you think it should be, then put it in the water and see if it floats like you want it to. Move stuff around until your happy and anchor the stuff in place, then if possible run the boat at speed to see if it handles correctly. Even after your done and start using the boat, you'll end up moving stuff around again.

 

[SuzukiChopper]

Re: Center of gravity and weight

So what do you plan to do if it sits too high?

This is why I'm asking. If it sits too high at a stand-still I'm wondering if there is anything I could even do? Should I even be worrying about it?

If it sat higher after you rebuilt it, either you changed what was there, or the old foam was waterlogged, if it was waterlogged then you returned it to where it would have when new. Knowing the center of gravity will do you little good at this point, just put everything where you think it should be, then put it in the water and see if it floats like you want it to. Move stuff around until your happy and anchor the stuff in place, then if possible run the boat at speed to see if it handles correctly. Even after your done and start using the boat, you'll end up moving stuff around again.

I was hoping there was a way to find out where the CG SHOULD be so that while I'm figuring places for batteries, storage, etc I could place everything on dry land fore and aft where they would be and see if I'm even close to having a boat that isn't overly bow or stern heavy. This way if need be, instead of having 2 batteries up front, with storage and the starting battery aft, I could maybe have 2 aft and one in the bow. I'm probably splitting hairs but I just want to plan it all out before I start wasting sheets of plywood.

 

[oops!]

Re: Center of gravity and weight

ondarvrs got it suzuki.

one of the things to watch out for in boat building is getting too complicated.
you can kill yourself with the detailes.......the early mfgr's mostly "guessed at stuff".....they just made boats they thought the public would like.

id say build what and where you want.....but keep in mind the total weight you are adding.....ther uscg max weight is your guide........if the max is 2900 lbs and your hull and motor are at 2000......that means you can add 50 lbs based on the fact that you will have 4x200 lb passengers and 50 lbs of gear.

before i did the hull ext i was really worried about the cg of the boat and the plaining point at what speed.......truth is thet the center of graviety will move as you use fuel! .....just keep everything as low as you can and keep it light as possible.......when you get in the water you will know if you have too much weight in one area or side.......

now.....i see the garage is insulated......get yerself a heater in there and get atter bud

 

[SuzukiChopper]

Re: Center of gravity and weight

Garage isn't insulated yet... just dealing with the cold

Thanks for the "calm down" gents... wasn't sure if I was over thinking things or not, hence why I asked. I'm going to build it like I planned it and try and make things as versatile as possible in case things need to be moved.