Mild Steel Limits?

[Spence]

This may be a bit late but could you ask the person transporting your boat to place it on 8"x8" wood timbers rather than 4"x4"? That would make a big difference as you would be able to slide a deeper structural steel member under the boat. If it's not too late, you could use your already fabricated tubes in the vertically stacked position rather than side by side.

You know that might do. The total height now on a 100 inch trailer wheel base is 3ft(bed height) + 3.5"(wood) + 6'6" cabin height. On top of that the mast will be placed sloping forward, height unknown.

So I would be concerned with the top heavy height of the load on cornering, and the overhead clearance with mast, but yeah it would increase the capacity of the beams substantially, although it's true the weight is located lower down on the keel. I'll see if that could be done.

What would you guys think about my changing the spans as indicated in this drawing. I have the option to have loaded at the same time the trailer the boat is sitting on. I would remove the undercarriage just leaving the frame. I didn't mention it because the wheels are splayed a bit due to the weight(bad decision by someone) and it's used just for yard moving at the marina. I was just going to leave it there, but I could use it to effect the moments to our advantage if possible. The height increase is another 3inches for frame.

Note also I think the 126inches for total span is more accurate than the 140 in the original drawing, since now I know the wheel span of the hauler's trailer.

Thanks for all the help guys.

 

[RichH]

Anything you can do to reduced the span length of the beam system will make it stronger and with less deflection under load.
Anything you can do to make those beams 'taller' (and weld-stitched together) will do the same; but, the 'taller' they are the more chance of each beam to 'rotate', thus cross beams running along parallel to the centerline axis of the boat become more important to 'hold' the cross beams under the keel in place.
;-)

 

[tkanzler]

Anything you can do to make those beams 'taller' (and weld-stitched together) will do the same; but, the 'taller' they are the more chance of each beam to 'rotate', thus cross beams running along parallel to the centerline axis of the boat become more important to 'hold' the cross beams under the keel in place.

Beat me to it. The advantages of four tubes on the flat is that they won't try to roll or fall over, and with them stitched into pairs, they're essentially mats, and aren't going anywhere. With a factor of safety of roughly 2 on bending, or better if the span is reduced, anything more is overthinking it, IMO. That's assuming some minimum material strength, absence of flaws, solid end support, solid bearing of the keel to the beams (no tendency to slip, like with a curved keel profile as viewed from the side), and so on, and so on.

 

[Spence]

Thanks all, you've given me a lot of info. I guess this is the point of departure in this exercise. I'm welding in the jack struts and going over my welds. The beams I'll run another seam just in case. I'll raise it up 6inches or so off the bed, then suggest everyone have a few beers. This should test the tear stresses. (After a couple beers maybe I'll have the guys jump up down on it, ....kidding!).

I paid the equivalent of flight tickets to some vacation for it so it will dent the account somewhat but it's not earth shattering if it drops, except for the heart of an old salt. I'll proly spend the futile attempt of trying to put Humpty back togeather again, to the chagrin of my missus, who thinks I'm generally nuts anyway, and not specifically.

I've built a few wooden boats in my time, so this is the first glass I owned. I'll have the rigging and sails, which makes it 3/4 the way home for a wooden sailboat project, maybe a Picaroon.(actually the rigging and sails are worth more than the boat.)

The farmers have a saying "don't name anything you intend to eat", well i have one for sailers, "don't name any boat until it's safe at drydock"

I already named it after my departed Dad, hope that isn't bad luck in seaman lore.

As Arnold says, I'll be back.

 

[Spence]

Got the boat, and we chose a spot between 2 walnut trees. We placed the jacks under and she lifted. Over 144in span, the flex was approx 1inch for the 3 X 6 stitched beam under the ballast. The flex was slightly less closer to the prow. These bends remained constant over 2 hours with no added support.

To make it even more safe and before anyone climbs aboard, I then installed 2 wooden posts under the keel. I then brought the jack screws down 3 turns so to have the posts take up some of the weight.

Now I'm going to winterize her with a cover. In the spring I'll start work on the trim, remove the rudder and check for "punkieness" if any and fix that, and do some cosmetic keel work.

 

[kloudie1]

Glad to hear that it turned out just fine! Word of caution, Spence.. Make sure that the cockpit is draining and not collecting snow or the drains ice up ..could very quickly apply a lot of extra load to the support posts and beams.. Looks fine!

 

[dscribner]

Now that she's up, get additional posts under the steel, mid point. Post directly under the keel will take all the bending stress out of the tubes. Home depot 4x4s will do just fine.

 

[Spence]

I'm with you pal. I'm going to drain the bildge if any and run a dehumidifier under the tarp drained to the scupper while I can do it before the temperature freezes. I heard that fresh water bidge between ballast parts can cause ice up to the point strong enuff to pop GRP keels from the inside.

 

[Spence]

Now that she's up, get additional posts under the steel, mid point. Post directly under the keel will take all the bending stress out of the tubes. Home depot 4x4s will do just fine.

Good idea. I'm going to put in crushed stone tamped in well. Then i have cement blocks with a wedge timber on top which the beams will lower onto for the winter.