Blocking for under Wing Keel on 1987 C34

[Les Luzar]

I agree with Ralph, that looks like some kind of structural crack in the hull that will needs a professional opinion rather than a Catalina Smile which should be horizontal along the hull to keel joint. I too would be concerned about this crack.

[Roger Blake]

Ralph and Les...yes, had it professionally checked...and the crack did not pentrate to the interior (looks worse in the pic than it was). Had it structurally checked...all ok. No hard, or any, grounding. When I boat the boat, I stripped all the bottom paint off and repainted...there was no crack. Hauled out, sat over winter, prepped bottom for the season in Apr, and found the crack (it was more hairline...but I dremeled it out to get enough material in). Now, one could argue the yard may have dropped the boat, or damaged it in the sling...but I had no evidence they did something wrong...could not prove they caused the crack. Anyway, repaired it and went on my merry way...that was something like 6yrs ago and everything is still fine (know this, cause I again removed all bottom paint about 2yrs ago and no hull issues).

[Les Luzar]

Then your good to go....great!

[Ron Hill]

Roger : You have a structural fracture just aft of the wing.  I believe that yours might be exarbacated by keeping tooo much weight on the aft pads/jackstands.

I'd have someone of knowledge inspect your hull (especially from the inside).  I'd also sent a series of pictures off to Gerry Douglas at Catalina for his openion!!   Good Luck!   A few thoughts

[Ted Pounds]

Roger, Is that the prop strut in the lower right corner?

[Roger Blake]

Ted, it is the prop strut...crack was just forward of it.
Ron, I had it checked on the interior prior to repair. I brought 2 different companies in to look at it...before I dremeled it and after. The advice I was given, open it up in order to put repair material into it...so keep in mind, it was mostly a hairline crack that I opened up...but there were a couple of areas the crack was a litle wider (but not much more than hairline)...so I opened that area up more.

Others who have inquired: I did the prep work, had the professionals do the actual repair. I have had no issues since...this all was around 2004, so 8 yrs later and all is good. The only thing I did after the "professionals", was to do some light sanding to smooth down a small hump around the repair...figured I could get another .0001 knts out of her.

[Roger Blake]

Ron--To address your other comment, I had requested the yard start blocking the boat level or bow down, and add a stand behind the prop strut...they were not doing that before. So, I think you are probably right, improper blocking caused the problem. Then I changed marinas...8 yrs later, no problems...and I keep blocking either level or bow slightly down. If you think the bow down is not good, let me know. Thanks for the input.

[Roger Blake]

This is how I have the marina blocking now...since the crack. Ron, Stu, if ya think I got it wrong, let me know. I have one stand on the bow, 2 each along port and starboard, and one behind the strut.[attachimg=#][attach=#]

[Ron Hill]

Roger : What I'd recommend is that you block with 3 stands on each sides on either side and forget the stand on the bow (That's for a fin keel boat).  It appears that when they put the stand on the rear of the strut there was way tooo much weight put on it!!

As long as there is no break on the inside of the hull you should be OK with a fix in the outside. I'd gouge it out and use fiberglass / mat and glass to fill it in.  Then be very carefull on how they block the boat in the future . 

[Roger Blake]

Thanks Ron. That is what they did...glassed it in. Will move to three stands on port and starboard...you mentioned loosing the bow support (because I have a wing keel), what about the stern support (which may have caused the problem)? Just go with three stands each on port and starboard? Thanks again.

[Steve W10]

Mike, my point is that wherever you block, the centre of mass will act at the location I indicated.  The further forward you go means more weight that needs to be supported by the aft pads.

Obviously there is a blocking point on the keel that results in the 75:25 ratio, and my guess is that Ron's got it figured out, so if that's what you want to achieve, he'd know, so might be best to go for the 1/3 from the front as I think he mentioned.

As an aside... I value the opinion of Ron, and what Catalina told him about the 75:25 thing... but....  when I bought my boat the PO was still using the original Catalina shipping cradle.  Both that one and the adjustable cradle I had made later have the rear pads at a location on my boat that has neither a bulkhead or even stringers on the other side of the hull.  Consequently, at those points, I have minor surface cracks in the finish of my hull because of flexing.  Personally I will endeavour to move some weight aft, but I'm not aiming for quite 25%.

Steve

[tonywright]

Just to clarify. Ron said put 75% of the weight on the wing (ie the keel) and only 25% on the pads.   In other words, if your pads are causing the hull to flex, they are too tight and need to be backed off. You will find that the flexing causes doors to jam inside: a clue that something is not right..

Others have talked of "bow-down" storage. You want to be sure that any water still runs off the stern so be careful with that.  The boat will naturally settle on the keel a bit stern down, so lifting the stern seems risky to me: maybe even cause the kind of cracking seen in that scary photo.

We use a winter storage cradle (not a shipping cradle). When lowering the boat into the cradle, we let it settle on the keel before snugging up the pads. This avoids overstressing the hull at the pad support locations. We block under the cradle to make it level and to keep the rudder off the ground. We use double or triple the amount of blocks under the keel, since that is where 75% of the weight is.

Tony

[Ron Hill]

Mike and Guys : Something VERY important.  When using jack stands make sure the yard crew "thumps" the hull to find the bulkheads, as that is where the jackstand pads should go.

[Mike McDonald]

Tony,
Thanks for the clarification.   
Mike....

[Tom Soko]

Roger,
If your prop strut is in the lower right corner of the picture you posted, then I think you are correct that the vertical crack was not structural.  It was simply at the edge of the "filler" that is put around the prop strut during construction.  I've attached a photo of the prop strut without the filler, taken during a Woodland Hills factory tour in 2006. Gerry Douglas gave the tour and explained how the prop strut is installed.  This photo is actually of a C34, as the last C36, #2305, was finished and sitting outside.  Hope this helps.