How To Calculate Boats CENTER OF GRAVITY. Inboard to Outboard Conversion
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- เผยแพร่เมื่อ 16 ก.ย. 2024
- Easy way to calculate your boats estimated longitudinal Center of Gravity point when doing Inboard to Outboard conversion. NOT accurate but good estimate.
When doing I/O to OB conversion. You are in most cases adding much weight in back of your boat, and that must be compensated with floating bracket or the boat will sit on a ugly angle.
How to DESIGN engine bracket:
• Inboard to Outboard Co...
How to MAKE engine bracket:
• Boats Outboard Convers...
Good video. I converted a cat with twin diesel stern drives to quad outboards on a custom high floatation bracket.
A trick to get a very quick center of buoyancy on a boat is to find out where the main fuel tank is. The center of the fuel tank should be close to the center of buoyancy. Naval architects do this because that is one of the largest vatiable loads and you dont massive changes in attitude from full to empty. I did all my moment/torque calcs off of that point to estimate what I needed for additional floatation from the bracket. It worked out great. However, I was very familiar with my boat and new that the boat sat level full or empty. That was confirmation that the tank was installed in the center of buoyancy and suitable to run calcs off.
Sounds very nice project! What kind of boat and what kind of power? How are the topspeed and fuel economy now?
@@BCB-Boats-Media Calcutta 390 Catamaran converted from twin Yanmar 315 stern drives to quad Suzuki 300s. Top speed is 50mph and best economy is at 30mph .9-1.0mpg. Im still dialing engine height and props so I might be able to improve those numbers a little bit. All in all, a very successful project. I have a youtube video of splash day and a thread on the hull truth.
@@MadNataveFishing I checked that video. That boat looks so good with those OB.ees. Congrats about successful project 👍
@@BCB-Boats-Media Thank you. Yeah, I really like how it stretched the boat out. Cats have a tendancy to look boxy due to the tunnel + gunwale height so length helps sleak them out a little.
@@MadNataveFishing True! 👍
Interesting. So in your case you don’t have to change fuel tanks locations🤔 that’s very helpful.
Cant wait to see what that will look like with big yamaha OB🥳
Thanks!
Yes for the boats sitting angle I dont need to think about weight distribution inside the boat, but there may occur porpoising when driving on plane. If so, then i have to move weight towards the bow of the boat.
I cant wait either to see this thing on water! 👍😎🌴
I plan to put swimming platform with a bracket for twin f60s if I can find another 2011, or new 4stroke tohatso 90s, I'm a digger driver, I'll take it down the yard, sling it in a strop, then move back or forth until I can pick it up, and the boat sits balanced in the strop, I'm more worried about the effects of added length and weight on it's trailered balance point.
It might be that you have to get your boat little bit more forward on that trailer. If thats possible I think you will be fine :)
@@BCB-Boats-Media thanks mate, good idea 💡 👍
Are you sure you aren't underestimating the weight of the stern portion with its old engine weight and thus overestimating the forward sections? Also, what advantages does this bracket give you versus the stern drive?
The hull itself is so heavy compared to the engine weight and also the original IO engine is so much heavier than the OB, so I dont think I underestimated a lot. Bracket + OB gives you example better handling, much better efficiency, much lower maintenance costs and lighter setup.
This is America please use pounds and feet. liters and kilograms!
what the heck is that?
Thanks for your comment. Im not in America :) So pounds are pretty uncommon thing for me. But yes I always add pounds / feet into my videos (with text) because aprox. 35% of my viewers are from America.
This is Earth, have you heard of SI system??
How about learning the Metric system. Guess what, it's based on 10 and really easy to understand. Only in America do we use a system that is based on 12, 16, 32, 64...etc. There are no fractions in the metric system.
@@sagnhill True 👍
@@BCB-Boats-Media The only people in the USA who fight against adopting the metric system are conservative right wingers. They see 5cm or 5km and freak out.