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OEM 26X trailer bow support roller plus CB support

Posted: Mon Jul 02, 2018 9:59 am
by Tomfoolery
I've been meaning to do this for years, as it's hard to get the boat onto the trailer without dunking it so far the goal posts are fully submerged, which allows the stern to drift around. My marina ramp is steep, so it's best to keep it shallow enough that the goal posts are just above, but then the bow bunks are out of the water enough that I can't get the bow into them. Once in, I'm good.

So I added a roller to the bow end, just behind the vee-bunk. Victor's (vkmaynard) new trailer provided the impetus to get off my lazy bum and get on it.

viewtopic.php?f=11&t=26541

Rather than add a new cross member, I used the existing channel that supports the small bunks. I had two pieces of 4x4x1/4 angle (probably A572), so I cut one in half and drilled them for 3/8" bolts for the 12" roller. The other is being worked right now for the CB support, but I'll get to that.

I fillet welded each one to the underside of the cross member, both sides of the cross member, after clamping the assembly to locate it all and removing the roller assembly.

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See next post . . .

Re: OEM 26X trailer bow support roller plus CB support

Posted: Mon Jul 02, 2018 10:03 am
by Tomfoolery
Finished product, after adjusting height so roller groove root is even with nadir of the two bunks.

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more to come . . .

Re: OEM 26X trailer bow support roller plus CB support

Posted: Mon Jul 02, 2018 10:19 am
by Jimmyt
Sweet!

Anxious to see if it helps eliminate the need for mac- bumping.

Re: OEM 26X trailer bow support roller plus CB support

Posted: Mon Jul 02, 2018 10:49 am
by Tomfoolery
Probably not, as I'll adjust it with the boat on the trailer so that it just touches. The angles it's bolted to aren't supported other than the welds across the bottom flange of the cross member, which is adequate to boost the bow into the vee bunks, but it would need better bracing (a different arrangement, actually) to support the boat while bouncing down the highway.

It's really there to lift the bow into the blocks without having to dunk the trailer as far into the drink, and maybe reduce the wear on the carpet (I replaced the carpet while I was at it). Maybe keep my delicate size 12 dogs dry, too, so I don't get slimy footprints all over the boat when hauling. :P

Re: OEM 26X trailer bow support roller plus CB support

Posted: Mon Jul 02, 2018 11:43 am
by Tomfoolery
In the works is a centerboard support forward of the middle bunk, as I keep Mac Bumping® too hard, flexing the trailer and allowing the CB to drop enough to get jammed. That's when I forget to retract it fully, because I need some CB (and rudders) to steer onto the trailer, and I usually remember to pull it up, even after it's in the bow block but before I start driving the tow beast up the ramp. Looks like this. :x

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From the clean area, you can see how far I had to bump it that time.

I'm using the other piece of 4x4x1/4" angle I had laying around, drilled to bolt to the cross member, and drilled to take a little block of PT 2x4 with bunk carpet (carpet is for looks only).

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I'd be drilling the frame to mount it right now, but mother nature decided to have a thunderstorm now, so it'll have to wait until later.

Re: OEM 26X trailer bow support roller plus CB support

Posted: Mon Jul 02, 2018 3:22 pm
by Jimmyt
I managed to put my :macm: on the trailer the other day with a bit of board down. Lucky I didn’t destroy it while coming up the ramp to the parking area. Actually, lucky my buddy noticed or I might have driven it home like that.

Glad I’m not the only one...

Have you ever noodled a way to correct for the angle issue that causes the nose block gap?

I guess I could strap the back of the trailer up to the boat while it’s floating and winch it tight. Reversing the winch and nose block might be more practical (but a lot less entertaining at the ramp). I’ve even considered a moveable v bunk at the nose such that you could raise it 2 inches or so during loading. Then when you pull up to the parking lot, just drop the front bunk down to settle the bow into the V notch. Was hoping you would solve it so I wouldn’t have to tax my pea brain with it.

Looks like some nice enhancements. Hope the weather breaks for you. We’re in daily thunderstorm mode here.

Re: OEM 26X trailer bow support roller plus CB support

Posted: Mon Jul 02, 2018 4:47 pm
by sailboatmike
Wow thanks for the awesome pics, this is one mod that is very high on the list, however I intend to make mine roller the permanent bow resting place rather and just use the bunks to keep the bow in place.

Maybe if you would of welded the plates to underside of the cross beam you would of got enough strength to only rest on the roller, but me being me I would have a bolt going through the plate and beam as a complete fail safe (who trusts welding anyway, especially when I do it :P ).

Re: OEM 26X trailer bow support roller plus CB support

Posted: Mon Jul 02, 2018 6:39 pm
by Tomfoolery
CB catcher, for excessive use of the Mac Bump® coupled with inadequate retraction and securing of the CB, which I've done twice so far, and will do again.

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Two 3/8" x 1-1/2" galvanized bolts, with 4 flat washers stacked behind the angle to pad the cross member out to the same plane as the strip welded to the bottom of the channel (factory method of reinforcing that joint). 1/4" galvanized bolts holding the wood block to it, same as all the other bunks.

It really doesn't need bunk carpet, but it would look odd without it, and I still had a fair bit left over from the last bunk replacement job along with SS staples, so why not.

I'll put up a couple of pics when the boat is on the trailer.

Re: OEM 26X trailer bow support roller plus CB support

Posted: Mon Jul 02, 2018 7:09 pm
by Jimmyt
That came out nice! Looks factory.

Re: OEM 26X trailer bow support roller plus CB support

Posted: Mon Jul 02, 2018 7:11 pm
by Tomfoolery
sailboatmike wrote:Wow thanks for the awesome pics, this is one mod that is very high on the list, however I intend to make mine roller the permanent bow resting place rather and just use the bunks to keep the bow in place.
I may try that yet. But my biggest need was to get the bow onto that bunk on a steep ramp, and also onto it on a shallow ramp without dunking the tow beast all the way to the driver's door. :P
sailboatmike wrote:Maybe if you would of welded the plates to underside of the cross beam you would of got enough strength to only rest on the roller, but me being me I would have a bolt going through the plate and beam as a complete fail safe (who trusts welding anyway, especially when I do it :P ).
The angles actually do overlap the bottom of the channel, and are welded both sides. I didn't seal weld the flange depth, but the trailer will rust away before there's enough corrosion in there to worry about. OK, and I didn't want to lay on my back and do the grinding to clean metal plus overhead welding in the heat.

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It's possible the angles can hold the weight as built, even with the roller rather far aft of the attachment point, but it wouldn't take much to add a plate to carry the shear to the channel web which would remove the bending moment at the aft weld joint. But I didn't want to block easy access to the bolts, and I was lazy and just wanted to git 'er done as it was pushing 100 F in the garage. :P

I'll take a few measurements and analyze it for strength. It's what I do at work a lot, but often just use eyeball engineering with this kind of stuff. :wink:

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Re: OEM 26X trailer bow support roller plus CB support

Posted: Tue Jul 03, 2018 12:14 pm
by Tomfoolery
Back of napkin analysis shows it can support 500 lb vertical at 36 ksi bending stress, which is yield stress for A36. I don't know what the trailer is made from, but the angles are almost certainly A572 grade 50 (50 ksi yield), as they're drops from some building fabrication job, and that's about all that's used these days.

Welds are not the weak point in this case, but bending in the angle at the welds is, plus welding weakens it a bit. The angle the boat hits the roller at sends the loads to the attachment close to the cross member, though, so it should be adequate. I guess we'll find out soon enough. :wink:

Re: OEM 26X trailer bow support roller plus CB support

Posted: Thu Jul 05, 2018 7:58 am
by Tomfoolery
Loaded the boat yesterday. Bow roller worked great, and I had the vee bunk well out of the water, which at my ramp means the tennis balls on the goal posts were also above water. No stern drift when loading, but I still had some problems getting the bow onto that roller, which is common as it's a narrow target (12" roller). Some side bunks about mid-ships, like many others have (Sumner for one, I believe) might be useful here.

But the bow just rolled right up and into the vee bunk. I did drain the ballast first, which always helps of course.

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The roller is holding some of the weight. Can't really see it in the photo, but it's slightly squished. But the wimpy support angles are not visibly deflected, so I don't think I'll bother to reinforce them. I'll get a better idea of how much weight is on the bunks vs roller when I splash it again, from the marks and amount of carpet squish.

Re: OEM 26X trailer bow support roller plus CB support

Posted: Thu Jul 05, 2018 8:02 am
by Tomfoolery
And the CB support seems fine. It might be supporting a little weight, but that doesn't matter.

Before:

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After:

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OK, so I did make sure the CB was secured before pulling the trailer up the ramp, as I leave it down a little so I can steer. But if I forgot when I bumped it into the chock, it still wouldn't fall and get the boat stuck.

And yes, it needs bottom paint. :|

Re: OEM 26X trailer bow support roller plus CB support

Posted: Thu Jul 26, 2018 8:36 am
by Tomfoolery
Here's a short video of me loading the boat with the new bow roller.

https://www.youtube.com/watch?v=WadeW3q9LXI

The false start in the beginning is because I scraped the goal post just enough to knock the bow to port. You can actually see the goal post deflect. I do this almost every time, but until I saw this video, I didn't realize I was scraping that starboard goal post. I always thought I was missing the little vee bunk and running along side of it, though there are no scrap marks on the slime to prove it. Because that's not what's happening. :|

I also got the swing CB hooked on the rear bunk, so I couldn't back up to correct until I took it out of reverse and allowed it to rebound forward slightly. Then I pulled the CB up. I always keep it down a little for loading, and sometimes pull it up just before I hit the trailer. And sometimes not. Like this time.

The bow roller worked beautifully. I probably could have powered it onto the trailer, or hit it faster, but this was my first attempt using the roller, and I didn't know what it would do. The vee bunk and roller are fully out of the water, whereas without the roller, I have to get that bunk into the water most of the way.

This ramp, in Orleans, MA (Cape Cod), is super shallow; the opposite of my home ramp on Lake Ontario. I stopped just short of the driver door over the water in this vid. Last year I had to bury the rear tires in the salt water, and step into deep water, to get the trailer low enough to load. I think my rear tires were just touching the water this time.

Pardon the prominent view of my keister, but I'll suffer the indignities for the greater good of sharing what I consider success with all you presumably interested fellow Mac sailors. :P

My one regret is that I didn't think to have my son video the bow pulling away from the chock as the boat is pulled up the ramp, necessitating the Mac Bump. Maybe when I re-launch in my home marina, I'll have him video me winching it back into the chock, and pulling it back up the ramp. For educational purposes, of course. :wink: