Hi Ron, Thank you for reading Good Old Boat magazine. I've been working with Karen and Jerry for over three years now and they are great people who put out a great magazine. I encourage everyone to subscribe!
No, I don't follow all the treads, but this one did catch my eye. I notice Stephen didn't specifically say for what boat the trailer was being fabricated, but it seems he owns a 34+, so I'm assuming it's for that boat. It's my understanding that at 11'-7" beam the 34+ will need some sort of wide load permit to tow it very far, but I'm sure Stephen has looked into that. With regard to the finding the location of the Longitudinal Center of Gravity (LCG), in order for the boat to float on her lines, the LCG has to be in line with the Longitudinal Center of Buoyancy (LCB). We did not do detailed weight studies at C&C to find the LCG, but we did find LCB from the Lines Plan. I don't have the data sheet for the 34+ (Rob Ball may have it, though), but the data sheets that I do have (LF39 and C&C 40) show an LCB location of 53.6% and 53.9% of the Designed Water Line (waterline not including skegs and rudders) from the forward end of the waterline (Station 0). The CG of the keel generally was located a few percentage points forward of the LCB in order to induce some bow down trim, as well as to compensate for crew weight aft. This "ballast lead" was a full 5% for the race oriented 40, and only .1% for the more cruising oriented LF39. Keep in mind, though, that the LCG of the boat should be forward of the axis of the trailer to induce some tongue weight. I believe a tongue weight of 10% of towing weight is often recommended. I'm assuming this is at least a dual axle trailer, so you may have some flexibility in that regard. I hope that provides some help, but certainly allow some room for fore and aft adjustment of the boat on the trailer to fine tune the weight distribution. I should emphasize, of course, that all this is offered for guidance only and should not be taken as definitive, since I do not have specific information on this boat. . Good luck with this. Rob Mazza On Tue, Oct 4, 2016 at 11:51 AM, Ronald B. Frerker via CnC-List < [email protected]> wrote: > Rob Mazza (sp?) from the list did a design article for Good Old Boat about > the center of buoyancy etc. It would seem the CG would be close by. > IIRC it was about a third back from the leading edge of the keel. Not all > boats are the same, but it's a good starting point. > Rob, are you tracking this and have something to suggest? > Ron > Wild Cheri > C&C 30-1 > STL > > > > ------------------------------ > *From:* Marek Dziedzic via CnC-List <[email protected]> > *To:* "[email protected]" <[email protected]> > *Cc:* Marek Dziedzic <[email protected]> > *Sent:* Sunday, October 2, 2016 12:22 PM > *Subject:* Re: Stus-List Center of Gravity > > Probably a bit further forward. My first guess would be to look for the > lift > points and expect the CG is half way between them. > > The lift points, usually, are somewhere around the aft end of the companion > way (bulkhead) and around the chainplates/bulkhead around the mast. > > I don't know your boat in particular, but from the experience (for the last > 10 years I regularly participate in hauling out and launching around 100 > boats each spring and fall), I would say that it is a reasonably good > educated guess. > > Marek > > -----Original Message----- > From: CnC-List [mailto:[email protected]] On Behalf Of Stephen > Thorne via CnC-List > Sent: Sunday, October 02, 2016 12:05 > To: [email protected] > Cc: Stephen Thorne <[email protected]> > Subject: Stus-List Center of Gravity > > > Folks I am in final stages of new trailer fabrication and need to identify > approximately where CG is for boat for placement on trailer. Original > owner > manual doesn't define CG. I am thinking towards trailing edge of keel but > this is somewhat of a guess. Any thoughts to clarify or estimate CG would > be much appreciated > > Stephen Thorne > 34+ > DejaVu > 770.722.2848 > Sent from my iPhone > _______________________________________________ > > This list is supported by the generous donations of our members. If you > like > what we do, please help us pay for our costs by donating. All Contributions > are greatly appreciated! > > > _______________________________________________ > > This list is supported by the generous donations of our members. If you > like what we do, please help us pay for our costs by donating. All > Contributions are greatly appreciated! > > > > _______________________________________________ > > This list is supported by the generous donations of our members. If you > like what we do, please help us pay for our costs by donating. All > Contributions are greatly appreciated! > >
_______________________________________________ This list is supported by the generous donations of our members. If you like what we do, please help us pay for our costs by donating. All Contributions are greatly appreciated!
