New Bow stop question

[Friscoboater]

I had a new bow stop and winch stand made for me the other day. I was going to attach with some unbolts, but they just did not provide the stability I wanted. So I ran !/2" X 7 inch grade 8 bolts through the trailer frame and cinched it down. It is solid as a rock, but i started thinking... did I hurt the strength of the trailer by doing this? It is a 3"X5" rectangular tuning, and I thought that three holes on the horizontal axis would not hurt it, but I always second guess. I still can weld it on if I have too.

What do you guys think?

Here is the old and busted one

 

[tbird175]

Re: New Bow stop question

This modification will not be a structural problem. You have actually added some strength to the tubing with the plate securely attached to it.

 

[UncleWillie]

Re: New Bow stop question

Remembering my Physics from way too Long ago, you did very little damage.

The side plates are carrying the weight.
The top and bottom of the box carry the Yaw loads in the turns.

Assume a box girder, loaded downward in the center of a span and supported on both ends.
The upper half of the side plates are loaded in compression.
The lower half is in tension.
The exact centerline carry no load at all.

Now flip that thought on its side and consider the top and bottom plates.
The same principals apply when executing a turn.
The holes in the center are a very minor weakening factor.
You will commonly see lightening holes in the center of beams when weight is an issue.

Now depending on how tight you made the bolts, you may be crushing the side plates causing them to bow.
That is NOT a good thing!
If you want to sleep well, get all anal about this, open the holes a little more and weld a piece of tubing in the holes top and bottom.
That will carry the load around the holes in the horizontal plates and eliminate the crush load on the side plates.
The box girder will actually be stronger than you started and the winch post will break off before it pulls out!

The tongue of the trailer does not carry much load to begin with.
Consider that two strong men can likely lift the tongue off the ground and 10 strong men still have no chance of bending it, you likely only weakened it by less than 5% in the turns and 2% vertically.

So now it is only 9.5 times stronger than needed instead of 10 times.

 

[Friscoboater]

Re: New Bow stop question

I thought I was doing ok. I might do the weld in sleeve thing.

Thanks guys.

 

[90stingray]

Re: New Bow stop question

I would have welded in place. Makes it look better and more like a custom trailer. But I understand bolting it on too. You could cut the extra threads of those bolts to clean it up... otherwise should be just fine.

 

[Scott Danforth]

Re: New Bow stop question

i would add some anti-crush sleeves. this will keep the fasteners from deforming the tube.

 

[Friscoboater]

Re: New Bow stop question

I was going to weld it on too, but my 110 welder will not penetrate the plate enough.

 

[mk4713]

Re: New Bow stop question

I would weld her up too. When in doubt weld it and beef her up a bit. I have no clue where u can take it in Frisco to have someone weld it up. There is a few places in Mckinney that may help ya out. On 380 and airport road is a metal fence maker. He makes the ornate fencing and doors. I need some welding done but never called to see if he would do it. I would'nt trust the bolts and tubing alone.

 

[jeeperman]

Re: New Bow stop question

While your messing with it you could flip the rear bolt over and use an eyenut on top.
Then use a safety chain or turnbuckle to the bow eye.
Or have anchor loop welded to winch stand base or that brace.

 

[The_Kid]

Re: New Bow stop question

If you are worried about strength add another plate under the tongue. It will also spread the load from the bolts over a larger area.

 

[ufm82]

Re: New Bow stop question

Scott beat me to the comment- use some tube inside to support the tongue tube. I use galvanized gas tube for use inside tongues and it works great. Cheap enough at the hardware store, cut it so it fits tight in the tube and tighten the bolts down.

 

[Jlawsen]

Re: New Bow stop question

I was going to weld it on too, but my 110 welder will not penetrate the plate enough.

We almost never weld them on because if we decide to change something in our boat and that changes the weight we want to be able to adjust the bowstop so we can maintain the correct tounge weight. What you did is fine and you can adjust it if you need too. You're only going to have a couple of hundred pounds of vertical weight on it. If you ever need to move it just plug weld the old holes up.

 

[H20Rat]

Re: New Bow stop question

pics can be deceiving, but can you use your winch handle? It looks like it would be running into the hull...

 

[Friscoboater]

Re: New Bow stop question

It does not hit the bow.