6 x 6 Pressure Treated Posts

[Johnbro]

I wouldn't use a 6x6PT across the top as your top beam. First of all, you don't need PT unless you have ground contact or the wood is constantly wet, which you won't since it's up in the air. Second, a 6x6 will be very heavy, difficult to get up there, and won't offer as much strength as a built-up beam will.

If it was me, I'd just sister the two 2x12s (hem-fir) with some blocking in between and call it good.

as to the question of how long the cantilever can be, two 2x12s on edge would make a strong beam--if it's not quite strong enough for the load it will flex a bit (just like a tree limb sticking out over a river that some kids have used as a rope swing). I'd use some Simpson strong tie metal to anchor it to the two posts as further insurance.

 

[Dutch445]

Here is an update with maybe a little better drawing:

I have on order a swivel attachment for the rope. SPIKER, this may get the effect you were mentioning. Also, a picture of the pier. The 20ft 6x6 posts are placed right at the end of the narrow part of the pier. Hopefully the word document gives a better rendition of what I am trying to accomplish.

Congrats on your waterfront , it's beautiful!!! It makes me jealous as I used to own a piece myself till I lost it in a divorce, I doubt I'll ever be able to make it happen again. Enjoy it!
(sounds like you do!)

 

[lakngulf]

Second, a 6x6 will be very heavy, difficult to get up there, and won't offer as much strength as a built-up beam will.

If it was me, I'd just sister the two 2x12s (hem-fir) with some blocking in between and call it good.

Please expound on this. Sorta have an idea but could use more details. Distance of the post from outside to outside is 7 feet. I want the extension over the water to be seven feet from post if possible. Can I do this with the beam approach?

 

[lakngulf]

Well I forged ahead with most of my original plan. It may not be all that pretty but I think it will be enjoyed by grandsons (6,3,2,4 months). Poppa will have to give it a try also.

Of course, the water has to come back up before any swinging. Each year our lake is drawn down 10 feet.

I tested the rope and there is almost no give when all my weight is on the rope. There is some give when simulating the type of swinging that will be done from the pier. The "swing around" does cause some rocking of the posts

 

[EddieWalker]

I've been confused on what you were trying to do, so didn't say anything. Seeing the picture makes it all clear to me. Must have been the bald in me!!! LOL

That sure does look like a lot of fun!!!!!!

Eddie

 

[weldingisfun]

Hey Eddie, that was a good one. Instead of having a BLONDE moment, you had a BALD moment.:laughing:
Now wait a minute, what is my excuse going to be, I'm neither blonde nor bald?