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Discussion Starter · #1 ·
Well the arch is getting defined, and Iâ??m down to the wire.

Here's some penciled sketches of tops I could live with. They are side view and the structures are the console and full-width bench seat. No bracing is shownâ??and there will be plenty. That 3/4" plywood bench seat top is going to see A LOT of the stresses from the radar arch. It will transmit forward/backward stresses to plates welded to the boat's sides and up/down stresses go to the bench seatâ??s newly braced bulkheads.

Looks like we have warmer weather coming up. That's good for curing epoxy for all the doublers and stuff I have planned for that seat.

Part of me says keep the bars away from my head. Drawings 1, 4 and 5 accomplish that.








After driving in yesterday's rain, another part says have an aft bar for a wrap-around isinglass option. Drawings 2 and 3 do that.





The console is only 18" wide, and I want the bars to be spaced at least 2" out from the console's sides.

The tubing bender does a 6" radiused bend with 1.5" tubing. So, by the time I do two 90s, there will only be 10" of flat area to use at the top. Think I'll just miter the corners at the top and get the full use of that area.

I'm also tempted to use 1.5" OD .083" wall 6061 T6 aluminum tubing in lieu of sch 40 aluminum pipe. The tubing is half the weight of the pipe and there's only one small bend that I can prolly get away with if we heat the area. Ya tubing flexes more than pipe, but parallel tubes with cross members welded here and there should stiffen it up considerably. A LITTLE flex is actually desired, because it doesn't impart such a shock to the mountings.

What's a good lightweight material to make the top from? Needs to be strong enough to hold the radar and VHF base holding a Galaxy antenna. Carbon fiber would be cool, but it causes galvanic corrosion to aluminum.

Your thoughts?
 

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#1 or # 3.....

#3 looks stronger than #1, but it's your call as I don't know how it sits relative to your hieght, or the width of the counsel.

#3 also gives you the Eisenglass option and as well as that swept look.

Let's here some other thoughts...

Cheers, Bill




â??If your not part of the solution... you're part of the problem"
 

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Discussion Starter · #4 ·
>can you pencil in a 6' tall person?

The plan is to have the lowest structure 6'4" above the center of the deck. I'm 5'11" and Dan is 6'2" (he claims).
 

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Kurt,
I looked at the bender today and really could not tell if the forms we had talked about were there, this bender is a dinosaur....

I'll take a picture tomorrow.....


Neill
 

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You have neglected the ONLY area where strength counts.

THE MOUNTING!!!!!!!!!!!

Unless the console is stronger and anchored a lot better then I think it is, it is the weak point. It is a long lever arm from the top to the floor.

I would run the arch to the floor and make sure it is well connected. Bracing to the console is good but no substitute for anchoring to the floor.

An alternate to bending is to make a template and go to teh muffler shop to get it bent.

Don
 

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Discussion Starter · #8 ·
Dayum! I hate it when chicks think of things. The wife read my post and immediately said: â??Why risk smacking your head with aft-mounted uprights and just run the clear material from the top to the console?

DOH!

Hereâ??s the pic, altered to show clear material. BTW: I married friggin Mary Poppins, and she can sew this stuff with her fancy schmancy Swiss sewing machine--or borrow a friend's power machine. She can get clear material darn cheap, so if the thing gets yellowed or scratched, you just throw it away and make another.



So anyways you get the best of both worlds: uprights away from my knoggin, and a windshield/sprayshield.

Now go back to the kitchen wench!

Kurt

PS Taurus: Thank you for the picture. It would be easy enough to build, but I would lose the windshield option. This boat can be REALLY wet.
 

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Discussion Starter · #9 ·
>You have neglected the ONLY area where strength counts.
>
>THE MOUNTING!!!!!!!!!!!
>
>

Hey Don:

Here's my bracing scheme. The weak point is anchoring it to the (aft) floor (ya, the most important part) as there really isn't much structure there. I'm afraid to rigidly connect it to a cross member for fear of ripping it off the hull. My fix is to make the footprint as large as possible to move the fulcrum forward--where there are solid structures and connection points. This will reduce the lever effect on the aft mounting bolts.

At worst, If weâ??re gonna get slammed for hours, Iâ??m going to make cables to go from either side of the transom to the corresponding corners of the top and another one from the bow to the front of the arch (though I don't think that one will be as important). These cables might be good to have for trailering too as the boat resonates on some freeways and Iâ??m sure that will stress the structure.

Here is what I had in mind. Green represents new bracing. Those long diagonal braces basically go under the chair and really wouldn't be in the way. They will be attached to the bench in the center so Euler will be happy (no more than 20:1 for a tube in compression).



The REAL fix would be to pull the console and floor, increase the number of crossmembers and double up on the floor around the console. May have to do it eventually, but I'd rather not add the weight.

Keep in mind this is not a tuna-chasing boat. Most of our trips are under 40 miles and I always plan the trip so the ride home in will be down wind according to the forecast--which is usually correct, given where we fish.
 

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WOW

I think I got TOOOOOO much of your attention.

I don't think you need to go beyond the ice chest (I guess that is what it is).

Most of the horizontal braces between the verticals are for looks on most tops. I think only the middle one is needed.

Don

In my former life, my specialty was Aero-Servo-Elasticity. A combination of the non-steady aerodynamics, control system, and dynamic structural effects.
 

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"I married Friggin Mary Poppins!" :D That was funny! Why don't women wear watches?...........Because there is a clock on the stove! }(
 

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Discussion Starter · #12 ·
>
>In my former life, my specialty was Aero-Servo-Elasticity. A
>combination of the non-steady aerodynamics, control system,
>and dynamic structural effects.

I just read an article about the B2 bomber's GLAS (gust load alleviation system). It had to be added when the Air Force changed the bombers flight envelope (two years after the contract award) to include low altitude, high subsonic flight--basically fly the same mach number at any altitude. This change made the B2 the only plane to have gust loading be the deciding factor in the design rather than maneuvering loading.

With the GLAS enabled, the pitot static system senses gusts and "weathercocks" the plane into them before the stress even hits the wing. It does this by moving huge elevons (larger than most fighter's wings) at over 100 degrees per second. Not bad for something developed in the 80s.

Oh, if you look up GLAS in Google, it might point you to the moveable "beavertail" in the back center of the aircraft. It's called the Gust Load Alleviation System, a leftover from the previous design. That was for the early design--back when the wing's trailing edge was a W rather than the sawtooth it is now. If it weren't so far along in the design, that beavertail would have been removed altogether.
 

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Is the arch going to be mounted to the consol? The bayrunner consol is pretty weak and would be subject to twisting with an arch tied to it. I think your arch is capable of supporting the radar and windshield. But the problem I see is that arch tubing will also be used as hand supports. Guys will constantly be swinging around the consol with one hand on the arch......alot of stess will be from that alone.

I have thought about building an arch for my bayrunner too. The best structural design would be to have a broad base to avoid the fulcrum effect like you mentioned. However you would be losing valuable deck space by having four arch "feet" tied to the deck.

I would simplify the design by just using 2 pieces of heavy duty angle iron mounted to the front corners of the consol and weld a supporting cross bar on top between the two. Bolt on a piece of plexi-glass for the windshield. It won't look as good as the ones you designed but it would be less inviting for guys to hold on to.

Peter
"Trusty Rusty"
18' Bayrunner
 

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Discussion Starter · #14 ·
>Is the arch going to be mounted to the consol? The
>bayrunner consol is pretty weak and would be subject to
>twisting with an arch tied to it.

As I received the boat this was the case. The console and the bench seat seemed to move independently. Since then, I've more securely attached the console to the bench seat in front of it, and it REALLY stiffened that rascal up. Now I'm gonna beef up the bench seat even more and Tim Taylor it to the console, making them one unit. I'll also use backing plates where the arch is bolted to the console to spread the load.

I don't totally trust that console either. I may go for mounting option #5 where two of the arch's legs are mounted to the bench seat rather than the console. I'd think a well-epoxied and bolted in 2x4 underneath each leg running the width of the bench would distribute that load to the bulkheads quite well.



The plywood that is the top of the bench seat will see most of the loads when this thing bounces. Ever tried to bend plywood along its plane? As the console rocks forward, it will try to push the bench seat forward as well. I've already added a bunch of bolts and plates to hold that seat in place, and it really stiffened up the boat.

The weak part now will be the welds on the side of the boat where the seat's bulkheads are welded to the side. I'm going to address this by welding an angle piece along the hull, with the flat surface resting on the plywood. The plywood's underside will be doubled up, epoxied all to hell and have T-nuts installed on the underside to accept the bolts going through the angle. That will take the stress off the 90 degree welds on the bulkheads.

Time to start with the long lead time items--the wood. Two coats of CPES, then two coats of regular epoxy. Nice weather for curing epoxy....finally.
 

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I was going to say that I liked design 4 and 5 the best. I think we have the same boat....mines an 86 westcoaster bayrunner with a 40 hp mariner. I re-mounted my consol on top of the middle bench for more deck room. I also stiffened-up the consols base for a little more stability......but it still twists a little.

Peter
"Trusty Rusty"
18' Bayrunner
 

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Here's my lovely piece of tin:

http://www.allcoastsportfishing.com/photos/showphoto.php/photo/4873/sort/1/cat/500/page/1




Peter
"Trusty Rusty"
18' Bayrunner
 

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Discussion Starter · #17 ·
Hey Pete:

If your console is 18" wide, this rod holder assembly will prolly fit. I won't be able to use it on the next one. Probably will be selling it.

 

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I could always use more rod holders but unfortunately it won't work cause my bait tank is in the way.



Peter
"Trusty Rusty"
18' Bayrunner
 
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