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 Post subject: Re: Mast Support Fail
PostPosted: Fri Aug 10, 2012 5:18 pm 
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kayakman7 wrote:
I absolutely agree with your statement; but what I did worked.
Kman, you are correct. It does. We just swapped out the new crossbars on the TI3 and I was forced to re-calibrate my thinking about V-Brace adjustments.

The 2011 hull was having furling issues (common on TI's) due to the lack of clearance between the mast and the bearing plate. The ring was sitting on the plate. It required adding 3/8-1/2" of stainless washers around base pin to raise the mast enough to achieve clearance.

During the install, we noticed that the factory adjusted V-brace was pushing out the bottom of the hull, creating an obvious hump. We loosened everything to neutral (no Vbrace pressure exerted on the hull) and found there was still was a tight fit for the mast. Expanding the brace only made things worse. What was required was compression!

After about 5 negative quarter-turns the hull squeezed into shape, slightly pulling the hull bottom and mast cup upwards. This FINALLY allowed the mast to rest/rotate freely on the pin. This is the only way I can see to effectively RAISE the mast other than shimming the pin.

After our adjustment, the bearing plate clearance was perfect. We even allowed for some mast bending (the lever effect).

So my feelings at this point are:

1. Hulls do vary, so don't take Hobies, or my advice as gold. Check it and do it yourself, if adjustment is needed.

2. If you over-extend the turnbuckles, you will run the danger of deforming the hull and cracking it at the V-frame base.

3. If the mast/furling ring are allowed to constantly contact the bearing plate, this could lead to furling rings coming loose, cracks in the crossbar welds and those crossbar/mast failures which look so catastrophic.

4. If you over-compress, you could potentially pull the brass V-brace anchors out of the hull.


Last edited by NOHUHU on Sun Aug 12, 2012 7:31 pm, edited 1 time in total.

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 Post subject: Re: Mast Support Fail
PostPosted: Fri Aug 10, 2012 6:33 pm 
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The Adventure Island must use a totally different mast support/Aka bar mount than the TI. On the AI, the distance from the bottom of the mast support tube (where the mast base sits) to the top of the roller bearing housing is 10-5/8th inches. This remains the same no matter if the assembly is in or out of the boat, tight, loose or otherwise V-Truss. It cannot be adjusted. It is a fixed assembly, top to bottom. The hull has no effect on it.

The only way to raise the furling drum in regard to the roller bearing housing would be to shim the bottom interior of the mast support base, as Nohuhu mentioned doing by dropping washers in there. That raises the mast itself, inside the mast support tube.


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 Post subject: Re: Mast Support Fail
PostPosted: Fri Aug 10, 2012 10:11 pm 
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Tom Kirkman wrote:
The Adventure Island must use a totally different mast support/Aka bar mount than the TI. On the AI, the distance from the bottom of the mast support tube (where the mast base sits) to the top of the roller bearing housing is 10-5/8th inches. This remains the same no matter if the assembly is in or out of the boat, tight, loose or otherwise V-Truss. It cannot be adjusted. It is a fixed assembly, top to bottom. The hull has no effect on it.
On all my AI's the turnbuckles control the aka Xbar hight compaired to the mast drum. :?

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 Post subject: Re: Mast Support Fail
PostPosted: Sat Aug 11, 2012 12:08 am 
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I'd always thought the AI/TI used pretty much the same system with some minor updated changes. My original AI had two sets of V-Brace locking nuts.
I've always thought the adjustment of the V-Brace was a bit 'hit and miss'.

It would be good if Hobie released a proper technical bulletin on this.
Matt, JB, BC... anyone? :)


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 Post subject: Re: Mast Support Fail
PostPosted: Sat Aug 11, 2012 3:11 am 
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Stringy, I just poked my head in the AI with the old female-style mast cup and the V-frames seem the same to me, other than the scale, due to the different sizes of the AI/TI hulls.

Tom, I don't mean to be harsh, but every statement you just made is incorrect.

The trick here is that there is subtle, but measurable deflection of the plastic hull near the center hole where the top of the mast receiver is attached. This area between the xbar bolts flexes like a tight drum when the turnbuckles are over/undercranked. The mast cup rises or falls with this tuning, and with it the step plate pin on which the new masts rest. I was able to see around 3/4" total travel from my adjustments.

When the mast rides too high over the bearing plates, you can lower it by expanding the turnbuckles. When it is too low (riding on the bearing plates) you should be able to raise it by compressing the turnbuckles until the pin touches and lifts the mast.

These actions also flex the hull bottom near the V-frame base so they need to be done carefully. Hobie does not document them, so it's easy to misunderstand and miscalibrate.

My observations are based on recent experience with the TI. Variations between plastic hulls happen and may require different adjustments. You and others are welcome to try them yourself, and correct me if I am wrong.


Last edited by NOHUHU on Sun Aug 12, 2012 7:32 pm, edited 1 time in total.

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 Post subject: Re: Mast Support Fail
PostPosted: Sat Aug 11, 2012 4:49 am 
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Mine simply isn't made that way. Turning the turnbuckles in any direction, contracting or expanding, has zero effect on the height of the mast furling drum and the top of the roller bearing plate. The roller bearing plate is bolted to the mast support tube. The geometry of this assembly is unaffected by anything you do to the hull, up or down. The mast support tube does not stretch - the 10-5/8th inch from the bottom of the mast support tube to the top of the roller bearing plate is set in stone, at least on my AI.

Over-expanding the V-Truss may well break something, but neither it nor the hull can pull the top of the roller bearing plate further than 10-5/8th inches from the bottom of the mast support tube. These pieces are, for all intents and purposes, a single unit.

Again, your's may be made differently than what I have here. I know there have some changes in these assemblies in the last few years, perhaps some running changes as well. Is your roller bearing plate bolted to the top of the mast support tube? If your pieces are separate, then I would certainly agree with you that the roller bearing plate can be move further (raised) from the mast support base pin (lowered). However, if they are bolted together as mine are, then you have a one piece assembly with a fixed length.


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 Post subject: Re: Mast Support Fail
PostPosted: Sat Aug 11, 2012 11:09 am 
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Well,after a couple weeks, the new main hull has arrived from the dealer. It looks like a bit "greener" dune color and has a different/smaller graphic near the stern, but looks solid. I have attached to the original akas/amas with Permaflex Anti-Seize (Thanks for that tip!)

I have put up the mast and unfurled/furled the sail, and it seems to work well (except for the ongoing issue of the furling line wanting to wind/jam under the spool... any ideas on how to prevent this?)

Also, I installed a strap around the mast cup and fore mirage well for a little added strength/insurance the next time I'm going to weather:
https://sphotos-b.xx.fbcdn.net/hphotos- ... 8527_n.jpg

There is also a slight bulge in the hull underneath the mast cup. If I adjust the nuts on the V-support to bring it upward, will it draw up the hull a bit??? (I'm afraid to adjust anything below because it seems confusing... although I did tighten up the nut just a bit on the base of the mast cup when I went around and snugged up various screws/nuts.)

I plan to get it out on the water this week, so we'll see how it goes...

Now, the question is: What should I do with the defective main hull?
(e.g., patch it somehow, cut a foot of the stern and install a marine ply transom, part-out, recycle)??? It still has a good rudder, centerboard, blocks, fittings, etc.)
https://sphotos-b.xx.fbcdn.net/hphotos- ... 5742_n.jpg

Thanks for all of the great input and support.

Take care, all!

Scott


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 Post subject: Re: Mast Support Fail
PostPosted: Sat Aug 11, 2012 11:58 am 
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Location: sarasota,fl
Guys:
You are both right actually.

I have installed several mast cups on several TI's (never any AI's). From my understanding of how it works, right or wrong this is the way I install the mast cup and adjust the braces to insure a stress free install...
With the unit disassembled I first put the mast cup into the hull and screw it down to the deck.
I then lower the v braces till they make contact with the stud and tighten the stud down.
I then go top side and install the AKA crossbar, the outside clamps only at first.
I then take the 3/4 x 1 x 5 inch aluminum spacer and see how close it is to fitting into the space. on several occations I had to crank in the V brace turnbuckles inward (compressing the hull) in order to get the gap close to the 1" height, on some hulls it started out around 1/2" to 5/8" too wide.
Once the gap between the AKA crossbar and the mast reciever is around 1 1/8" I then install the spacer bolts and tighten them down with locktite.

NOHUHU is correct when he says by turning the turnbuckle you can vary the deck height.

However Tom is correct when he says the height of the mast reciever in relation to the AKA brace is a fixed height determined by that 1 inch aluminum spacer. Once everything is tightened down the distance is fixed.

Now here is the twist, because the attachement point is so far off center, it is easy to flex the opening which normally U shaped wider or narrower just by cranking up or down on the turnbuckles. You can probably vary that height up to around 1/2 inch just by cranking up or down without much ill effect (if any). So NOHUHU is correct.

The height is supposed to be a fixed height so Tom is right.

Now here is something else I discovered.. The rotating drum on the mast is epoxied onto the carbon fiber mast (at least on my old (early 2010) mast it was ( I have not looked at my new mast yet). I bumped it one day transporting and the collar actually slid on the mast so when I placed the mast in, all of a sudden it was rubbing on the bearing plate on the AKA, it had never done that before so started checking and discovered I could slide the collar up and down just by bumping it. I used a piece of large PVC tubing and a large hammer to drive it back to the correct position. It hasn't moved since, or give me any more problems....

For what its worth.

Bob


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 Post subject: Re: Mast Support Fail
PostPosted: Sat Aug 11, 2012 12:08 pm 
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The deck height has no bearing on the distance between the mast support pin and the roller bearing plate. The distance between the pin and the plate is fixed by virtue of the assembly being a single one-piece unit once bolted together. You cannot stretch it.

Even if I could raise my deck height by a foot, or drop the hull bottom by two feet, the distance from the mast support pin to the roller bearing plate top would still be 10-5/8th inches. The roller bearing plate and the mast support tube are bolted together. You cannot stretch them apart.

Here is a cut-away of the assembly on my AI:

Image

The mast support tube and roller bearing plate are part of the same assembly. You cannot move the pin nor the plate in such a way that the distance between them can be increased. It is a fixed 10-5/8 inches, period.


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 Post subject: Re: Mast Support Fail
PostPosted: Sat Aug 11, 2012 1:02 pm 
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Tom:
Thats why you are correct they are bolted together and the height is fixed. However I just went out into the garage and pulled the mast reciever out to show you. With my finger only I can flex the plastic attachment point (where the 1 inch brace bolts to) 1/4 of an inch with almost no force (just my finger). It's a flat piece of plastic around 5/32 thick and 2 inches wide, it can easily bend. At least thats how the TI is constructed, I have not looked closely at an AI.

So you are correct when you say the height is fixed.

However NOHUHU is also correct when he says he can adjust the height of that bearing plate easily by cranking up or down on the turnbuckles. He is bending that 5/32 thick x 2 inch piece of plastic to adjust bearing height. Knowing my plastics, I'm pretty sure you can moderately bend that plastic mast reciever a little without any ill effects, however I wouldn't go over board, it will break at some point, then you need to buy a new mast reciever.

So I'm not arguing with you I am agreeing with you.

NOHUHU is cheating ( LOL) but hey it works.... ( I would do the same)

Can you go pull your mast reciever out and take a pic so we can see if it looks like this....
Image

Image

PS I didn't really pull it out of my boat, this was an extra. Don't pull your reciever out.


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 Post subject: Re: Mast Support Fail
PostPosted: Sat Aug 11, 2012 2:04 pm 
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You can bend the flange all you want, but the distance from the bottom to the top of the portion of the tube the mast sits in will remain the same, unless you can figure out a way to actually stretch it. I don't think you can do that without introducing so much force that something is going to be prone to breakage. Obviously, you can move anything with enough force, but I don't think any good design requires you to go to that extent to obtain any necessary clearance.

Perhaps we've just uncovered the reason that a few folks are having trouble with split hulls and the like.

Aside from the force and stress involved in trying to stretch a unified assembly, it is almost inconceivable that Hobie engineers would design something that would require great force and stress in order to obtain a desired clearance between 2 pieces, particularly when that clearance would be so easy to design into the part to begin with.

If the proper clearance between these pieces is 1/8th inch, why not just build it into the involved parts? (I think they did.) Just glue the furling drum onto the mast at a distance that is 1/8th inch more than the distance between the mast support tube bottom and the roller bearing plate top. It’s just that easy.

To have to force and thereby create mis-aligned pieces in order to achieve a known, desired clearance, just doesn’t make any sense. Such a thing amounts to extremely poor design. I don’t believe the AI was designed this way.


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 Post subject: Re: Mast Support Fail
PostPosted: Sat Aug 11, 2012 7:36 pm 
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...So, is it better to lengthen or shorten both of the V-trusses? I noticed that there was a slight bulge in the hull beneath the mast cup, so I tried to shorten both gradually maybe 1/4" (hoping that it would pull up the bulge); however, I am not sure that it did (or if it just pulled the deck downward?). I am resting the bulging portion on a volleyball (which is sandwiched between the trailer tongue and the hull) overnight... Maybe if I pour some hot water/towels tomorrow, it will help to flatten out the bulge...?

Thanks, again.

Scott


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 Post subject: Re: Mast Support Fail
PostPosted: Sat Aug 11, 2012 8:36 pm 
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SailScott:
My new TI (about a month old) also has a bulge on the bottom under the mast reciever (boat came that way). I have not done anything about it, I can't see it hurting anything, just looks funny. I wonder what it's all about (none of my old TI hulls had that).


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 Post subject: Re: Mast Support Fail
PostPosted: Sat Aug 11, 2012 10:15 pm 
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Fusioneng:
That's comforting to know... My last one had a slight crater (basketball dent-sized) just behind the forward Mirage well, conveniently where the stowage hatch was. So, I was able to work/push it down somewhat with hot water/towels. (Would a blow dryer used cautiously work, too?) The bulges below the mast cup must be a recent issue... harder to deal with maybe. Ideally, a nice flat hull moves with less resistance through the water (and much more aesthetically appealing!); however, unlike fiberglass boats, plastic boats seem to commonly have slight craters and bulges along the keel (where there is much more stress... and thus where there should be a LOT more structural rigidity than there is).
Thanks.
Scott


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 Post subject: Re: Mast Support Fail
PostPosted: Sun Aug 12, 2012 1:38 am 
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Scott and Fusion, in my opinion the hump is not a problem so long as the mast rides properly on the step plate and not the bearing plates. It just indicates that positive force is being applied with the turnbuckles.

However, if your furling ring has clearance issue (rubbing or too tight), then clockwise turns on both turnbuckles will compress the hull, raise the step plate and also remove some of the bulge.

Our TI had an excessive bulge and the mast was making contact. It came that way from the dealer. The mast, receiver and pins were all measured and found to be in spec. The only thing left was to make the proper turnbuckle adjustments (negative) for this hull. It did the trick and furling is much easier now. The bulge is greatly reduced.

I just did the exact same adjustment to an older style AI tonight. I was having trouble easing the sail so I added about 3/16" clearance above the bearing plates and things spin well now. (On the older style AI crossbars there are no spacers tying the receiver to the crossbar so adjustments take a few seconds and are a snap. But on the TI style crossbars you can do it as well).

As far as other non-structural dimples, dents and such, I think Hobie has suggested using hot/cold water for these cosmetic repairs. Heat guns are not the best tools for heating large areas (or mixing with water). :shock:


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