Center of gravity

Technical information and geeky boat stuff
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kurt swanson
Bottom Sanding Grunt
Posts: 3
Joined: Thu Aug 26, 2010 6:59 pm
Boat Name: Lobo
Boat Type: Pearson Renegade

Center of gravity

Post by kurt swanson »

I have a Pearson Renagade. I would like to know where the longitudinal and verticle canter of gravity is.
Hirilondë
Master of the Arcane
Posts: 1317
Joined: Thu Dec 28, 2006 8:50 am
Boat Name: Hirilondë
Boat Type: 1967 Pearson Renegade
Location: Charlestown, RI

Re: Center of gravity

Post by Hirilondë »

Welcome to the forum Kurt. You have great taste in boats ;>)

I can't answer your question, but even if you knew, what would you do with the information?
Dave Finnegan
builder of Spindrift 9N #521 'Wingë'
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Gresham’s Law of information: Bad information drives out good. No matter how long ago a correction for a particular error may have appeared in print or online, it never seems to catch up with the ever-widening distribution of the error.
kurt swanson
Bottom Sanding Grunt
Posts: 3
Joined: Thu Aug 26, 2010 6:59 pm
Boat Name: Lobo
Boat Type: Pearson Renegade

Re: Center of gravity

Post by kurt swanson »

I have a used trailer and I would like to convert it to not only transport my boat but also haul and launch from a nearby ramp. The ramp is steep which is good and bad. I am intending to install a sliding extension to the trailer in order to get the needed depth under the keel. I will also need to move the boat on my property over piece of road that slopes to one side. With the center of gravity, an engineer friend can calculate if I will have an overturning problem. I can't proceed with the conversion until I am sure I won't get into trouble during haul, launch or in transit. Any suggestions for finding the CGs would be appreciated.
Skipper Dan
Master Varnisher
Posts: 102
Joined: Wed Jun 30, 2010 2:58 pm
Boat Name: Jade
Boat Type: Pearson Triton

Re: Center of gravity

Post by Skipper Dan »

I just hauled my Triton back from RI on a small trailer. The weight is so low on these boats I cannot see how they could turn over on a road. They just look high and tippy. I cannot remember the name of the trailer outfit that make trailers for sailboats but you might try one of them. They must know a few boats.

Dan
Hirilondë
Master of the Arcane
Posts: 1317
Joined: Thu Dec 28, 2006 8:50 am
Boat Name: Hirilondë
Boat Type: 1967 Pearson Renegade
Location: Charlestown, RI

Re: Center of gravity

Post by Hirilondë »

Wow, interesting project. Good luck getting the information to proceed.

I just have to ask: What keeps the trailer from jack knifing and hoisting the rear of the tow vehicle when the boat is extended aft on the trailer when launching or retrieving? If you do succeed in over coming this and the other issues I bet you have the only trailer sailed Renegade of the 173.
Dave Finnegan
builder of Spindrift 9N #521 'Wingë'
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
Gresham’s Law of information: Bad information drives out good. No matter how long ago a correction for a particular error may have appeared in print or online, it never seems to catch up with the ever-widening distribution of the error.
Skipper Dan
Master Varnisher
Posts: 102
Joined: Wed Jun 30, 2010 2:58 pm
Boat Name: Jade
Boat Type: Pearson Triton

Re: Center of gravity

Post by Skipper Dan »

I think you float the whole boat rather than slide it in as you would a regular boat. The extended tongue lets the trailer just fall away from the boat. Quite a few Tritons are launched this way.

Dan
kurt swanson
Bottom Sanding Grunt
Posts: 3
Joined: Thu Aug 26, 2010 6:59 pm
Boat Name: Lobo
Boat Type: Pearson Renegade

Re: Center of gravity

Post by kurt swanson »

Thanks,
That is what I intended to do all along. With the fin keel though, I have some issues about how the boat would shift as the boat is pulled out of the water. The front of the keel will contact the trailer first because of the slope of the ramp, about nine degrees. Should I want the boat to sit level, longitudinally, at least two of the forward hull supports and aft supports would have to be adjusted; maybe several time as the boat is pulled out of the water. I might just allow the boat to float in at the nine degrees with the supports set for that sloped attitude and transport at that angle. A friend has a long straight keel on his boat and he restrains’ the boat from sliding backward during the haul. The boat rotates into the level condition as he hauls it up the ramp. With my boat it would be difficult to restrain the boat from sliding backward during the haul because I have no good point of purchase. The process gets complicated either way.

I am not familiar with the Triton configuration. How do you restrain it when hauling up the ramp?
The modifications of this trailer for hauling my boat are going to be expensive and I would like to have them all galvanized. This means that I need a pretty good idea of how this all will work before modifications are made.
Thanks again for your input,
Kurt Swanson
One Way David
Skilled Systems Installer
Posts: 183
Joined: Sat Aug 02, 2008 8:46 pm
Boat Type: Pearson Ensign
Location: Kansas

Re: Center of gravity

Post by One Way David »

I trailer an ensign, only 22.5'. It has a Triad trailer. All of their trailers are custom made for a specific application. You are correct in needing the COG to place this just ahead of the axle(s) on a shop built trailer. Otherwise bad things happen. You might ask for people that have a Renegade trailer to get specs. You might be able to get the info from Triad. If you were somewhere that had a lift that would let you experiment, put a pipe under the keel and roll it fore/aft until you find the center. The lift to keep it from tipping over. BTW this later technique I hereby label the redneck way. Probably what I'd try.

Dave.
Never finish all your projects or you'll be bored.
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