Canvas

Foggy, I know I know, you make me laugh sometimes. But I want everyone's advice. I sort and think and sort and think. Eventually I develop my own strategies and things work out.

Dr Bob, Thanks. Thorough job explaining. Can't wait to get started.

Tom, Wish I had two weeks of time and a treadle machine to boot.


Thanks, everyone.
 
Foggy, I know I know, you make me laugh sometimes. But I want everyone's advice. I sort and think and sort and think. Eventually I develop my own strategies and things work out.

Dr Bob, Thanks. Thorough job explaining. Can't wait to get started.

Tom, Wish I had two weeks of time and a treadle machine to boot.


Thanks, everyone.
 
Thanks for posting your drawings. I see one potential problem with it. Where do you plan to get in and out of the boat? The handle is on the bulkhead but you have a support beam in the way. If you plan to get in in the middle of the cockpit I don't think the vertical tube will provide enough support.
 
Now that I am on my computer, and not my phone, I can add some more to my previous comment. The top provided by King Marine Canvas has a different configuration that allows us to enter the boat near the bulkhead. There are a number pictures on their web site https://kingmarinecanvas.com/cdoryboats.html that you can look at as you design your system. Image 7 has a good picture of this. The back support attaches to its support bracket with clevis pins so one can fold the top forward. For trailering I don't bother taking the top off. I just fold the top forward and attach the folded frame to the handles on the bulkhead with a webbing strap to keep it tight. When cruising I unzip the top from the strip that attaches to the cabin and fold the top against the back frame. Three straps hold the top and frames together. This way I reduce my windage significantly without having to remove the top and put it back up every day.
 
Tom Hruby":o9esogfr said:
Thanks for posting your drawings. I see one potential problem with it. Where do you plan to get in and out of the boat? The handle is on the bulkhead but you have a support beam in the way. If you plan to get in in the middle of the cockpit I don't think the vertical tube will provide enough support.
Click to expand...

Tom, You found the Big Question of the design. I was wondering if anyone would question this: is the width and height shown sufficient to get in and out comfortably?

The height of the Bimini is higher than any I've seen. @6'8" it allows a near 4' vertical entry. That seems fine. The width is 30" except where the diagonal crossbar is located. Question: 1) is the crossbar in the way 2) is 30" x 48" enough.

Another member mentioned that visitors were always grabbing the Bimini frame to go in and out and questioned whether the frame could long sustain that abuse. Knowing this I decided to build it strong enough initially to take such use.

On Friday I'm taking the boat to the Bimini shop to possibly make a mock up and also to decide whether to use 7/8" or 1" tubing.

Upon seeing this plan the Bimini Guy also mentioned that he may recommend using one pivot and having all three bows hinge off of one centered pivot. Sounds whimpy to me. But he has done this for years and I'll hear him out.

Thanks for your comments.
 
Yes. I see these photos. I'm sort of following the Blue boat. The different is an added bow 6" behind the cabin. I'm tall and for most of King Canvas's tops shown here I'd be stooping throughout most of the cockpit, not fun. By designing these with higher bows and also adding a bow close to the cabin I will be able to stand straight almost right away upon leaving the cabin. Also for many of these tops, the entryway width, as shown, appear to be much narrower than the 30" I designed into my version.




Tom Hruby":8ndlc08v said:
Now that I am on my computer, and not my phone, I can add some more to my previous comment. The top provided by King Marine Canvas has a different configuration that allows us to enter the boat near the bulkhead. There are a number pictures on their web site https://kingmarinecanvas.com/cdoryboats.html that you can look at as you design your system. Image 7 has a good picture of this. The back support attaches to its support bracket with clevis pins so one can fold the top forward. For trailering I don't bother taking the top off. I just fold the top forward and attach the folded frame to the handles on the bulkhead with a webbing strap to keep it tight. When cruising I unzip the top from the strip that attaches to the cabin and fold the top against the back frame. Three straps hold the top and frames together. This way I reduce my windage significantly without having to remove the top and put it back up every day.
Click to expand...
 
With the top zippered to the cabin top, I often unzip the top about 18 inches and fold the edge back. That way I can get in and out without having to bend down (I am 6'1"). Our frames are stainless steel and quite strong, but should not be used as a handhold. The strength of the frame is not the problem; it's the bracket that attaches the frame to the hull that becomes the weak point because there is always some play in it. Pushing or pulling on the tubing creates a lever that significantly increases the forces on the joint and can easily damage it.
 
Whatever you design I still think having the system with one frame on the pivot is critical so you can fold the system while either trailering or cruising. I know from experience with my earlier boats that it is a real pain to zipper the top to the frame every time one wants to use it; especially if it starts raining. Also, according to King Marine, the top should not be on above speeds of about 25 mph because the air vortices cause the top to flap and put strain on the seams. A three or four bow system can be designed with one pivot and back supports that is higher than the one by King Marine if you need it. So far at 6'1" I have not had any problems in the cockpit. The King Marine system provide about 6'6" in the cockpit. The door however is lower so I do have to scrunch down to get in and out.
 
Does this work better (below)?
What do you think of the entryway?
One_Pivot.jpg

Good Hardware like this 316 stainless should have no issues being a handhold. And I guarantee guests will grab it even when told not to. So since these fittings are easily replaced maybe I'll carry an extra or two.

By the way...I believe King Canvas would be citing CYA policy to ask you to stay under 25mph. I have Searays, Parkers and Grady's pass me all day long at 40-50 and that may be into a 10-15 knot wind. Their canvas is fine. So is King Canvas of such low quality that they're asking us to go much slower...I don't think so, they're fine. I believe they're just covering their tracks and being on the safe side.

End_Hardware.jpg
 
My bimini is on a 3 arch frame. There is one hard pivot point on gunwale and adjustable straps at the front and back. The single pivot allows the angle of the bimini to be adjusted and also allows the bimini to fold up against the cabin roof (just above the door) for storage, trailering, and simply when not using it.

Bimini in use
1020779_G.sized.jpg

Bimini stowed
P7280026_1_sm.sized.jpg

When the bimini is up, boarding is from the swim step or the gunwale by the lazerette hatches. The bimini is strong enough for a stability handhold, but not to swing from.
 
I see one potential problem with your latest design. The aft strut is too long. When you fold it forward, it will extend quite a bit above the cabin top. I think a three bow design would be adequate.
 
Sobol, you were cheating by using that nice boarding step. Some of us have twins, ya know, and had to give that up, dang it!

Tom, I can still move the pivot even further aft but, as is, it settles nicely on the back of the Radar Arch (see below). If I move it back 4-6" more that would work as well and lower it on the arch to just above the roofline.
Arc.jpg

I can't add any more arc's like you see here. Not having a proper drawing compass I had to use dishes and pan lids to fudge the arc's. On that last Arc I used my largest pot lid, lol.
Do you think I should move the pivot aft. My thoughts were that this as shown stays out of the way of the door when it swings.
 
Agree with Tom. A three bow frame is adequate for the C Dory 22. You only want the end supports up and down, You want a single bow attachment to the gunnel which will be your forward bow, and then an aft bow, with the middle off the forward or aft bow.

Let the professional made the bows.
 
Tom shared the King Canvas photos of C-Dory's that they've done in the past. The three bow Bimini I'm having done will look like the Bimini in this photo. But for this year I will only commission the Bimini and not the sides $$$$$$. It will have the attachments for the sides next year an will have a removable connection to the cabin top. $3500.


IMG_1901.jpg
 
I have no idea if "Costa Track" is any better or worse than any other awning rail. However I would not depend on a double sided tape to hold it in place. I have used rails with a flange which could be screwed down--Yes, I know that the rail pictured can have screws in the bottom--and that those weaken the railing.

I would be more worried about distortion in heat than cold. Some of the PVC's will deform in Arizona type of heat.


As for trailering with canvas on the frame. I have seen too many damaged to do that. It only takes a few minutes to take the canvas on and off the frames--using zippers, not threaded into tubes. The best awnings will have all of the raw edges finished--those raw edges are what begin to frey. I had some of this happen on a trip across the US (as most of my trips were), even though the Bimini when stored was covered with a Bimini cover and then wrapped with line. You may have various boats pass you at 70 mph--I would say they are taking chances driving 70, plus you have no idea how their Bimini's hold up, or how far they are going. 20 miles, is much different than 2000 miles! Also remember that wind pressure squares with increased speed, not linear increase.

One of the King Canvas Bimini had the raw edges finished under the top, the other didn't. So quality can vary.

With 1" tubing, solid supports fore and aft, plus the full camper back up, mades the top much more ridged than smaller/lighter tubing and no camper canvas on the sides. With the Tom Cat Bimini I had, one could pull the boat to the dock with the forward brace and have minimal deflection. (I don't recommend this as a practice, but to show the rigidity.)
 
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