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Tomcat camperback canvas questions

 
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JMacLeod



Joined: 26 Jun 2018
Posts: 173
City/Region: Stuart
State or Province: FL
C-Dory Year: 2018
C-Dory Model: 255 Tomcat
Vessel Name: C-Shalom
Photos: JMacLeod
PostPosted: Sat Aug 18, 2018 6:07 pm    Post subject: Tomcat camperback canvas questions Reply with quote

Three Rivers Marine has a canvas guy on site that does all their C-dory's.
We're having him make us a full camper back with screens and roll up windows.
We've already discussed zippers at the roofline for easy boarding from the dock.
Are there any other tips for the support structure, attachments, or canvas that I should bring up to him?
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Rick from Maine



Joined: 02 Nov 2003
Posts: 308
City/Region: No. Berwick
State or Province: ME
C-Dory Year: 2000
C-Dory Model: 22 Cruiser
Vessel Name: Hunky Dory
PostPosted: Sun Aug 19, 2018 9:09 am    Post subject: Ideal Canvas Reply with quote

I think the ideal canvas should be/have:
1. A separate panel between the bimini and cabin roof with zippers on both sides to allow easy access.
2. The bimini should be higher than the cabin roof, to allow cruising without the panel between the cabin and bimini for cooling ventilation.
3. The whole camper canvas should be able to be assembled while standing on the cockpit floor.
4. The hem of the bimini should have radar reflective tape to increase the boat radar signature.
5. The support structure should be sturdy, as it will get pulled/pushed by people when docking/rafting.
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thataway



Joined: 02 Nov 2003
Posts: 20778
City/Region: Pensacola
State or Province: FL
C-Dory Year: 2007
C-Dory Model: 25 Cruiser
Vessel Name: thataway
Photos: Thataway
PostPosted: Sun Aug 19, 2018 1:58 pm    Post subject: Reply with quote

I would agree with "Rick"--except for the radar reflective material. The surface area of the hems are so small, and the effectiveness of radar wave frequency material is not all that good. Perhaps Rick has some information on this?

I used 1" SS pipe, on the Tom Cat. There were 3 bows and two vertical supports on each side so that the frame was totally free standing when the front panel was zipped out. Zippers in the front should start at the inside and zip outward, so you can open partially at the dock.

I mentioned a number of different vinyls in a PM to you. Be sure to get the best material for your purpose--there are trade offs, of clarity and scratch resistance, against the ability to roll the fabric up. Strataglass, EZ 2 C, Crystal Clear, are all high quality, pressed (not rolled) vinyl with excellent clarity and scratch resistance. I referenced a Sail-rite article. I opted for windows more easily rolled up, over the stiffer one with better clarity. But they had the scratch resistance and were 30 mil.

You want to decide if you want the clear vinyl to roll up--and how to protect it if you roll, vs hinge up at the top, and have velcro under the Bimini to hold it out of the way.

The type of frame support depends on your desires ref fishing--some want a top which slides all of the way forward to clear the cockpit. Others prefer the "Cantilever" design (I don't think that 3 Rivers has any experience with that).

You want velcro flap over the outside of the very forward zipper, and may want it over the second zipper aft.

You want all sewing to be done with UV resistant thread--"Tenara" is the most common. " Profilen" is another. Some canvas workers don't use it because it costs more and is a bit more difficult to use.. But it will last the duration of the Bimini--other threads will fail from the Florida Sun.

As for the canvas worker--see some examples of his or her work. Here in Pensacola, we have several--only one is good enough for work on my boats.

Here are a couple of photos of my Bimini frame on the Tom Cat. Note that it goes to the deck, not the pipe railing. Note that there are two vertical supports on each side, with quick release pins. There is a wide area to board thru. I have an extra hand railing on the cabin house aft, not necessary if your radar arch goes all of the way across. You want the hand hold as you come out of the cockpit to the side deck.




Note the aft hand rails have a cut out for the clear vinyl.


I had personal reasons for small windows in the side--and we did not put in insect screen--I probably would have insect screens and slightly larger windows in retrospect.



This is a photo of the extra hand rail--was on a 25, I didn't find any photos of the one on the Tom Cat. These are thru the overhang, so it is thru solid glass--easily done.


_________________
Bob Austin
Thataway
Thataway (Ex Seaweed) 2007 25 C Dory May 2018 to Oct. 2021
Thisaway 2006 22' CDory November 2011 to May 2018
Caracal 18 140 Suzuki 2007 to present
Thataway TomCat 255 150 Suzukis June 2006 thru August 2011
C Pelican; 1992, 22 Cruiser, 2002 thru 2006
Frequent Sea; 2003 C D 25, 2007 thru 2009
KA6PKB
Home port: Pensacola FL
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Rick from Maine



Joined: 02 Nov 2003
Posts: 308
City/Region: No. Berwick
State or Province: ME
C-Dory Year: 2000
C-Dory Model: 22 Cruiser
Vessel Name: Hunky Dory
PostPosted: Mon Aug 20, 2018 8:37 am    Post subject: ideal canvas Reply with quote

My cruising experience with other C-Dorys (all 22') is that they have very small radar signatures. When C-Dorys are behind me, they often don't register on my radar unless they have a radar reflector (typically, cheap Davis foam & foil types).

So, for around the same cost as a radar reflector, adding reflective material in the "roof eave" of the bimini is a cost effective way to increase safety, and has no downsides.
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thataway



Joined: 02 Nov 2003
Posts: 20778
City/Region: Pensacola
State or Province: FL
C-Dory Year: 2007
C-Dory Model: 25 Cruiser
Vessel Name: thataway
Photos: Thataway
PostPosted: Mon Aug 20, 2018 4:13 pm    Post subject: Reply with quote

Rick--what is this reflective material? How much is the radar signature increased? Please tell us exactly what the material is, where to buy it, and cite how studies which show how much it increases the signature. Actually the "Cheap" Davis radar reflectors perform quite well against many of the more expensive units. I have often carried both.

To be a good radar reflector, a material must be electrically conductive, flat and smooth. There have been "radar reflective flags"--they are a failure. Practical sailor did a study using household aluminum foil, retroreflective for light materials, and all of these were little better than the background. To have a reflective Bimini, it would have to be flat, and smooth surface--and at the proper angle to reflect the radar wave. The reason that the Davis foil reflectors work, is that the surface is perfectly smooth, flat, and the angles of the reflector are set to give maximum reflection.


The newer digital radars are far better at low signature targets at close range....in fact all modern radars are far better than 30 years ago.

I agree that the C Dory is a relatively low signature, but I pick them up quite well on the Garmin HD and the current Raymarine Quantum.
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