Trailer rollers

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Trailer rollers

Postby balder.matt » Mon Dec 23, 2013 1:39 pm

Have noticed recently that the trailer roller assemblies make kind of an impression on the boat hull as it sits there. What I mean by impression is that the rollers on one of the spots actually flex the boat hull some. I've noticed that some trailers have bunks instead of rollers, are these better for San Juan 21 hulls? Also I am considering replacing my trailer with something a bit smaller and more lightweight. I would like to trim some pounds because I will be towing my boat with a Subaru outback 3.0 H6. If you have any suggestions of a good light-weight but quality trailer with a less than 350 pound tounge wieght (with boat and sailing gear loaded) that would be very useful.
A side note is that I cannot get the centerboard to roll up all the way flush into the centerboard trunk. Is this normal for San Juan 21?

Thanks!
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Re: Trailer rollers

Postby kuriti » Tue Dec 24, 2013 6:04 am

I belive you are describing what they call "oil canning" of the hull. Basically it is flexing when it shouldn't. I am not the definitive expert on this, but yes, the more you spread the weight, the less likely it is to harm the hull. Just kinda depends on the total surface area on the bunk or rollers, more being better. Solution is to glass in bracing supports inside the hull (read: major pain in the ass). If your trailer is made for a bigger boat, that may be bad too. Say the springs are rated for 3000 lbs but your seagull-like sj21 is only 1200lbs. The springs don't compress when you hit a bump and all that force is transferred to the hull which is more flexible than the spring. So if you are already thinking of a new trailer, that would probably solve the problem faster and with less cursing, if not more money.

My keel stuck out about 2 inches before i dropped it for repair. I had a bent keel bolt and wear on the pin hole, so i am not sure yet if it will sit flush when i reinstall, probably later this week. Others will have a straighter answer.
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Re: Trailer rollers

Postby balder.matt » Tue Dec 31, 2013 3:57 pm

Thanks for the info Kuriti! My trailer is a bit larger than some I've see for SJ21s but doesn't seem to have an excessive set of leaf springs to make it stiff. It is an EZ loader with the extendable tongue. Not a bad trailer but it has the boat sitting up higher than other trailers I've seen which makes launches harder, even with the tongue extender. I'm thinking of maybe getting a new, larger roller assembly for the oil canning spot if I can find such an animal.
I would like to get my CB to roll all the way. I wonder if I do have a bent hinge bolt. It operated very smooth this past summer. Could it be an issue with my cable/pully assembly?
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Re: Trailer rollers

Postby kuriti » Thu Jan 02, 2014 9:19 am

If the keel is uniformly sticking out, not just the bottom half, then the pulley system is likely working fine. you can open the access hole on top of the keel trunk to see if the keel is hitting the stop bolt. if so, then that is as far up as it will go. if you haven't inspected all of the sheaves and cables, you need to do that ASAP. Keels falling freely into keel trunk = day ruined. Anecdotally, my keel bolt was slightly bent and the hole in the keel was oblong, but I didn't notice any ill effects in the keel, no wobble or anything. i still haven't gotten around to putting my keel back in, so i can't say if remedying that will make it flush. I am sure others could give a more definitive answer.
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Re: Trailer rollers

Postby kuriti » Fri Jan 03, 2014 6:58 am

Hey, by the way... i was looking at this guys extensive photo log of his rebuild and found this shot of his keel. this is about how much mine sticks out, so i am going to say this is normal. he didn't drop his keel, so arguably he has some sag, but if it looks like yours and mine, it is probably designed like that:

http://www.tommysolomon.com/photos/1981 ... large/#nav

this website is an invaluable source for "what stuff should look like".
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Re: Trailer rollers

Postby cklamp » Mon Jan 13, 2014 2:35 pm

Looks like Kuriti got you covered...

But... yes, the keel will stick out a little bit, that picture looks about correct to me.

And I'd replace the rollers with bunks, or if possible put many more rollers on. depending on the trailer it shouldn't be too hard either way. Oil canning is pretty common on these old boats. Mizu had severe oil canning as she sat on 2 short about 4' bunks... I eventually added two more to increase the load area, but am going to actually increase them from the 4x4' lengths I have now, and see if I can do 4x6' lengths this winter to support her hull better.

Later
C
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