Stretching a 22

M

mpmccoy

New member
I think I've seen one C-brat boat with an out board bracket like this one.TWIN.thumb.jpg

Does anybody have any experience knowledge or thoughts on adding one to a CD22? Aparently they would space my twins back from the transome and have positive flotation. Several manufactures make them and I've seen Skagits and Rossis with them.

Looks like it would provide a lot more room for the cockpit area.
 
I'd guess the boat will be very tail-heavy with that addition and you won't like the result at all. My 22 cruiser has a Honda 90 and a 9.9 and it's a little tail-heavy I think. Even with the 90 trimmed all the way down I need some trim tab deflection to run at something like a 4 degree bow up deck angle, which feels about right. I'm just guestimating the feel by watching tachometer vs boat speed and trying to optimize that. I looked at where the horizon off to the side lines up with the side window frames and calculated the angle from that.

The spray coming out of the side of the boat seems to be about under the driver's seat area, more or less. If it's choppy I can trim the bow down more and get a better ride at some sacrifice of speed vs rpm. Nice to have some control over boat attitude without having to move stuff around inside the boat.

I have a fuel flow gage system to install some time and I can further optimize the trim after that, but I'll bet the difference from what I'm running now will be small. I just like to play with stuff like that.

I'll bet the boats that come with those extended engine mounts have a different hull design or a different weight distribution from a C-Dory. I'd do a LOT of research before adding such an item. For instance, you could calculate where the new center of balance would be and try to load the boat to balance there for a test. You might have to put everything in the boat way at the back and have a couple of friends come along and stand back there, too. Even that might not be enough.

If your engines weigh 500 lbs and you move them back 3 ft, that would be 1500 ft lbs of moment change, which you could simulate by moving x pounds y ft and z lbs s ft, etcetera until all the x times y and z times s products added up to the 1500 ft lb value. That would simulate the balance change you'd get with your addition. You could see how it acts and then give up and move on to another project. Don't forget to add the extension weight and its distance to the 1500 ft lb value in the above example. I bet you'll get a big number and have a hard time moving enough stuff to simulate it, but you could move as much as you can and see if you like the result. If you don't, there's no point in going further.

(Maybe you should bring extra life jackets during the test.... :wink: )

Jeff
 
Also, the existing transom probably isn't designed for all the extra torque that would be applied by that extension. This is probably a bigger concern than the balance I was originally worried about.

The 22 C-Dory is a pretty ideal design. I'd be AWFULLY careful about basic changes. Details, yes. The basics, probably not.

Jeff
 
I don't see how you would gain any room in the cockpit unless you removed the splashwell and lazarette compartments. That would weaken the structure.
 
Such an extension designed by a naval architect specificly for C-Dorys could be a real plus.
I'll pass on one designed on the kitchen table.
 
If you're looking primarily for a larger cockpit, it would make more sense to enlarge the boat with an extension section added to the middle of the cockpit rather than adding to the end of the boat at the transom, as Larry says.

Dave added 2 feet to the middle of the cockpit to his CD-16 very nicely, as seen in this project:

C-Voyager's 24" hull extension

I'm not sure the cost vs. the space gained for either type of these undertakings is cost efficient, however, as compared with switching from one model of an existing boat to another.

Moving a cooler up off the cockpit floor and onto a bracket mounted above engine well can give you a quick 18" addition, by the way!

Joe. :teeth :thup
 
If the extension adds displacement it changes some of what I said. The original post seemed to show an extension that only moved the engine without extending the waterline or planing surface. Maybe I'm not seeing this one right, but the extensions I've seen at boat shows do not add displacement. I also couldn't tell for sure but it looks like Beer Thirty extended the hull. It also looks like he can't raise the main engine. Not a compromise I'd like to make. Maybe I didn't see it right.

Jeff
 
Since I found my transom of my 1984 Classic rotted and sole core damp, I removed the splashwell and the inner glass skin from the cockpit sole and transom. I really like the space in the cockpit without the splashwell and have been considering a hull extension as well. I've seen Beer:Thirty's custom-built engine bracket and corresponded with him about it; he's still real happy with the results. The approach Oldgrowth has taken seems to be working for him as well.

I'm more inclined to add to the rear of the boat in a manner that looks like I had cut the last two or three feet off a new Angler and added it to my boat; as opposed to a bracket-style extension. The structure would, of course, be quite different as the sole core would not be continuous and there would be additional stress placed on the transom at the corners since the splashwell's stabilizing influence would be gone. Current thinking would have vertical structural elements through-bolted to the rebuilt transom replacing the anti-flex characteristics of the splashwell, exterior fiberglass extended forward bonding the extension to the existing hull, and beefing up the interior with epoxied fiberglass where the transom meets the sole and sides of the hull. Since I've got to re-glass the sole and transom interior anyway it shouldn't be too difficult to add a few more layers for a stouter bond.

Lots to consider, but I think a 25-foot Classic would suit my needs and wants for a very long time. I also like the current flat transom style that allows for the main and kicker to be mounted side by side. Perhaps a permanent fuel tank will be mounted in the extension as well as more house battery storage and a built-in propane locker. I'll continue to consult with experienced boatbuilders as my design evolves.
 
Just a small point, by adding LOA to your boat, you may encounter different Coast Guard regulations. As I recall, there are regs that a 24 foot vessel must comply with that a 22 foot does not, such as flying an "at anchor" black ball and such. You may want to check on those so that you are prepared.

Up here with all the commercial fishing, there is liability that the recreational boat owners face should they impede right of way or cause the commercial fisherperson a loss of gear. Coastie boat (Maple) just paid a guy $6K for running over his nets, even though the Coasties were limited by their draft and the fisherman's nets drifted into the navigatable channel.

Also, the Coasties up here have warned that, due to the high percentage of recreational boating incidences on the West Coast, versus the commercial and charter boat incidences, law enforcement is being asked to focus on the recreational crowd this year.
 
Chivita,

You make a good point; I'd forgotten the size ranges in regard to federal safety requirements. It appears as though our boats generally fall into the 16 to 26-foot requirements according to the USCG Web site. I probably missed other categories of rules however, since I didn't see anything about the at-anchor ball.

http://uscgboating.org/safety/fedreqs/equ_refchart.htm
 
I wonder how many boaters even know what the anchor ball is, let alone own one? I have owned them for my boats over 40 feet, and probably used them a couple of dozen times in many years of boating.

Most brackets are not hull extensions, and only add minimal bouyancy at rest, not under way. I agree that most C Dories seem to be designed as the splash well is part of the structural part of the transom (although that can be adressed in other ways). Also the engine will be higher with the hull extension--probably by 2". If I was to add an engine bracket that, I would completely rebuild the transom, up to the height of the gunnel and tie the lazerette wells into the structure.

I wonder how many C Dories were designed by a Naval Architect? The origional ones I believe were designed by Ed Monk, but there have been multiple modifications, which I suspect were not run by him, and I also suspect that some models were not NA designed at all...
 
Bob,

The approach you described - as I understood it - seems to be an extrusion of the existing hull lines aft to a new transom. That's basically what I have in mind to do to my Classic. The existing transom would remain in place, sans splashwell, with the new structure providing that stability. The existing hull will be ground and beveled forward of the new structure for the epoxied fiberglass plies to grip; all the way around from the gunwale to sole to gunwale.

The issues I have concern about are the potential for porpoising and the overall change in weight distribution. I'm sure there's a way to calculate (at least approximately) the new materials weight and how much additional buoyancy I'll gain, but have yet to find an article and/or formula that is clear to the non-naval architect or engineer. I'd like to mount a permanent fuel tank in the new structure, but must be able to determine what kind of weight the new and improved boat will support well within the margins of safety.

If you, or others, know of an information source(s) to assist me in determining how to go about this I'd appreciate it.

Tom Herrick

In regard to the anchor ball, I found the USCG requirements at this URL:
http://www.uscgboating.org/safety/fedreqs/equ_nav.htm

The text, copied and pasted here, is as follows. They have diagrams as well on the Web site and in publications.

Lights and Shapes

To alert other vessels of conditions, which may be hazardous, there are requirements to display lights at night and shapes during the day.

Anchored Vessels

AT NIGHT: All vessels at anchor must display anchor lights. If your vessel is less than 164 feet/50 meters in length, then its anchor light is an all-round white light visible where it can best be seen from all directions.

DURING THE DAY: All vessels at anchor must display, forward where it can be best seen, a black ball shape.

Illustration of sailboat at anchor during the day, displaying a black ball shape suspended from its mast. Illustration of powerboat at anchor during the day, displaying a black ball shape suspended from a line running between the center of the boat's cabin and the prow.

EXCEPTIONS: If your vessel is less than 23 feet/7 meters in length, then it is not required to display an anchor light or shape unless it is anchored in or near a narrow channel, fairway or anchorage, or where other vessels normally navigate.

If your vessel is less than 65.6 feet/20 meters in length, then it is not required to display an anchor light if it is anchored in Inland Waters in a special anchorage designated by the Secretary of Transportation.
 
I have a freind who had a specially built "Striper" with an Armstong bracket. It was great with the added cockpit and freeboard and turned on a dime but with the motor it added literally 6 feet out beyond the boat, and that's not tilted. About 8' tilted. Think about that for garaging or storage. A 22 is probably 35' long with the trailer tongue.

Creates a bit of a problem if you fish larger fish as it is near impossible to walk one around the back of the boat. You need to really play them out big time away from the boat. We actually had a long cord with a clip on each end that we ran under the Armstrong such that if you hooked a lunker and it ran under the hull you could attach the clip to the rod and throw the pole overboard let it sink and retrieve it on the other side (then you just prayed he wasn't smart enough to go back the other way!)

Chris
 
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