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Speed boat seat frames

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  • Speed boat seat frames

    Like to say a big hello to the forums, I've been lurking for a few years now, just never signed up....anyways.
    A friend wants me to build some seat brackets for his speed boat, and already bought all the "neccesary" material. He wants me to weld together a pair of 23" high seat brackets out of aluminum 1.25x1.25x.125 angle. I'm just not sure that this will be strong enough to be used for seat brackets for this boat(600 hp-ish).
    And chance this material will be able to take the abuse?
    The old sead brackets were just pre-bent 1/2x1.25 aluminum stock, no bracing of whatnot. I was gonna link the top and bottom, and add cross bracing throughout.
    Thanks for any ideas and suggestions.

  • #2
    I have no clue what you're talking about.

    What the heck kind of "seat bracket" is 23" tall.

    If you want help, you've got to do better explaining what it is you're trying to do.

    As far as if the metal is "strong enough", that has everything to do with how the "bracket" is designed. Sounds more like you're describing a seat frame than a seat bracket.


    • #3
      Sorry, I should expalin them a bit better.
      These are a combo "frame/bracket", that anchors the seat to the floor of the boat. When completed, they will be 24 inches tall, 21 inches wide, and 20 inches deep, with a latching mechanism that allows the seat bottom to fold down and allow the user to stand upright and operate the controls of the boat. There is also a seperate 1/2 x 1.25 "strap" that the back of the seat will rest against, however, it is only held to the seat with a piece of cloth, and not anchored to the actual seat.
      Yes, I understand that frame design is critical to the strength of the overall structure, I am just curious as to whether it would be wise to use 1.25x1.25x1/8 aluminum angle for a frame that will be 24" tall, and whether the metal will have the vibration resistance to not crack around the floor anchor points, as well as the seat mounting points.
      I was thinking that some type of aluminum tubing would be a better choice, like 3/4" aluminum conduit for the legs, with a 1/4" thick base, as well as horizontal supports from front to back, and perhaps a x-brace or simple diagonal brace across the back.

      Thanks again.


      • #4

        Nothing personal, but you're asking questions that indicate a lack of understanding of the stresses involved and necessary for the proper design of the leaning post/seating setup.

        Over the years I have run performance boats by Cigarette, Apache, Fountain, etc, etc, and I've never seen a leaning post/seat that used square tubing. Larger diameter round tube is used for additional strength and also to avoid the sharp corners found on square tube.

        An absolutely stable support is critical when operating a boat such as this at high speed. Oftentimes in this sort of performance boat you employ both a driver and a throttleman. When the driver is also controlling the throttles/trim, adequate support is critical.

        Do you really have the background to be designing and fabricating a structure that could cost a life if it fails.

        PS. After sleeping on this one, I'm further convinced that you're "in over your head" on this project. NO qualified fabricator is going to use "aluminum conduit" to build bolsters for a performance boat. If you study the stand up bolsters with drop down seating that Fountain uses on their boats, you'll have a better idea about where I'm coming from. Flawed design coupled with inexperienced fabrication is a sure fire disaster.
        Last edited by SundownIII; 07-17-2011, 10:40 AM. Reason: Additional thoughts


        • #5
          I'm glad you feel that way.
          I thought about it, and am going to build it in a manner that i feel will be safe, reliable, and strong.
          Since this conversation is going nowhere, and arguing this point over the internet is useless, this topic is dead. I'll stick to lurking from now on.


          • #6
            Don't go off all butthurt now! If you only lurk you can't ask questions and get intelligent responses. Sundownlll was giving good advice, you need to be a little thick skinned around this bunch, but you will get good advice and sometimes more than you wanted or thought you needed.


            • #7

              ditto lol **** sundown was actually pretty dam cordial compared to alot of posts


              • #8
                Not butthurt, i'm used to dealing with sarcasm, smart asses, arseholes and the buttkiss, but I've usually found that on the internets, once a non-constructive post is up, and the peoples minds are made up, its not worth my time to try and convince otherwise.


                • #9
                  i'll bet if your friend took you out in his boat and put the hammer down; head into a light chop or cut a wake or two you might see things in a different light.


                  • #10
                    Originally posted by mikespenny View Post
                    Not butthurt, i'm used to dealing with sarcasm, smart asses, arseholes and the buttkiss, but I've usually found that on the internets, once a non-constructive post is up, and the peoples minds are made up, its not worth my time to try and convince otherwise.
                    Naaa, Not always true. Only if the OP comes back in self defense in total denial. Then he is eaten alive

                    Now back on topic. Your frame as you have descibed it is going to be angle? No it will not work for sure. Not even as a patio chair would it work. Angle used in that manner is very weak.
                    Boats do not have any suspension and literally pound the snot out of you.
                    This part is almost exclusively made out of 1 1/2" sch. 40 aluminum pipe. 6063 T-52 will bend nicely. If you do this with any less it will be simply embarrassing to everyone involved.
                    My mind isn't really made up here, BTW welcome to the forum.....I'm around these type of boats 24/7. If I walk out on my deck right now you can here them howling (seriously) I am sitting in my office in my welding shop that I live in typing this at 9 pm. My shop is full of and surounded guessed!
                    The design you suggest is simply too tall for the material and weight. It will wad up and break. Not even considering it will look weak and cheap.
                    Even the good ones crack up at times. I have welded a few back together over the years.
                    Sundown is right. Take no offense if you just want the basic truth. Just do it like he said. Big round tube. Don't believe us....simply Google bolster seats and go to images.


                    • #11

                      Now you've pissed me off with your juvenile comments.

                      If you didn't want to hear the truth, then don't ask the freaking question.

                      Just so you understand, I'm not exactly a newbie when it comes to performance boats. I was racing inboard hydros at 125 MPH+ when I was nine years old. I drove for OMC as one of their factory drivers from 1959-1966. Carl Kiekhaefer, former president of Mercury Marine offered me the job in January 1967 that Reggie Fountain later took in August of that year. That was to drive at Lake X, which was Mercury's high performance test center.

                      Don Aronow, the founder of Cigarette, Magnum, Donzi, Blue Thunder, and a few other brands of performance boats was a very close personal friend of mine. I was in his shop in N. Miami Beach in 1974 when Doc McGue set the Miami to New York speed record. Up until about four years ago I worked with the dealer for Fountain Powerboats for Maryland, Virginia, and North Carolina.

                      In short, I'm no stranger to performance boats and what goes into them.

                      The "hokie" seat arrangement you described sounds like something you'd see on a 12' aluminum jon boat with an electric motor, not something with 600+ HP.


                      • #12
                        Who cares...


                        • #13
                          Originally posted by Guardrail View Post
                          Who cares...

                          Sundown, I see your little buddy is back once again to toss in his well-reasoned response...though it would seem somewhat illogical for one who supposedly doesn't care to be following your postings.


                          • #14
                            Originally posted by Guardrail View Post
                            Who cares...
                            Well.... some one asking for opinions on building a Speed Boat Seat Frame should probably care or at least accept the advice from some one else that actually works/fabricates/repairs in the same field as the Topic but seeing as the OP decided that 3/4" AL Conduit is a safe, reliable, and strong material for this application perhaps you are correct...

                            who cares?

                            but just to be clear I want to understand the Logic:

                            Q. Will this material work?
                            A. No

                            "Ok, I'm going to use the material anyway"


                            • #15
                              Just to clarify
                              By "safe, reliable, and strong material", I am just going to do the proper leg work on my part for determining which type diameter/wall thickness of aluminum tubing is needed to have the neccesary strength when coupled with a proper design.
                              Again, considering that the factory frame was 1/2x1"-ish plate bent into a closed oval, I see no reason that a tubular structure, made out of 3/4" DOM 3/16 wall tubing welded to a 1/4 top and bottom plate, would not provide a strong alternative with horizontal bracing on the sides, and cross braces on the rear. Since it will be exposed to salt water, 6061 will be that alloy of choice. The conduit was a random thought, you are correct, it has no place in a real structure.

                              Sundown, I'm glad you have the backround in this, and don't take my previous comment as an insult(if you do, fine) but your initial post, as well as its followup was neither constructive nor helpful towards my goal, which when posting in a forum, non-constructive posts usually lead to nothing more than useless banter.

                              And to sum this up-
                              Owner wanted frame build out of his material, as a box.
                              I didn't think it would work, so i posted here, thought confirmed.


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