Hunter 356 hull deforms on travel lift

[JohnSn]

Hi All,
We just did a pre-purchase haulout of a '03 Hunter 356 we're considering purchasing. We had an interesting problem show up when the vessel was hanging from the travel lift slings.

First some background. The yard put the slings in the designated spots based on the stickers on the hull. On this lift, each sling is made of two pieces with a pin tying together the two halves of each sling. The problem I'm about to describe occurred with the aft sling and not with the fore sling.

When the boat was lifted out of the water, we noticed that the pin was about 2' from the centerline of the vessel. Right where the pin was- which was under the shower-, the hull was deformed inward nearly an inch. We put the boat back in the water and moved the sling. The hull was again deformed at the location of the pin. Then, we repositioned the sling so that the pin was on the centerline of the vessel. In that position, the hull didn't deform.

I currently own a Hunter 30 and haven't seen this problem before.
It sounds to me like Hunter 356 hulls might be built thinner or has greater spacing between the stringers in the vicinity of the shower. Or, perhaps this specific Hunter 356 has a thinner hull.

Has anyone else either seen this problem? Or never seen this problem?

Thanks!

 

[FastOlson]

Friend of mine used to own/operate a boat yard. He had a terrible time with a Hunter 28 one time -- every time they thought they had found a proper "hard point" for the poppets, it would deform a lot as the lift tried to let it settle onto the stands. He said that the thin layups on the Hunters were always a problem. While the hulls were/are strong enough to keep calm water out, they do have problems with *any* sort of 'point loading'.

OTOH, you get more interior volume for the dollar with those boats and that satisfies their owners just fine. You just have to know what you are getting for your money. If you buy it, ID and mark the 'sling lift positions' carefully, for the future.

 

[Jerry Clark H356 SV Persi]

There have been some support problems with some of the 356 in the area of the shower. Mine does not have the problem, but another boat in our marina did. The shower floor was removed and additional stringers placed and the floor reglassed in if I remember the repair correctly.

 

[Captain Larry-DH]

The pin should not be against the hull. Improper handling equipment for any boat - slings should not produce point loads. Cored boats are damaged by it.
If the pin is the only option it should have been well protected with padding. I’d blame the boat yard, if any soft spot or delamination results.

 

[chuckwayne]

Ditto on Jerry's comment - some 356's apparently were missing a stringer under the shower floor that allows the hull to deform. Escape does not have the issue, but her sistership, ONE serial number higher, does. the fix is to cut open the shower floor, add a replacement stringer, reglass the floor.
BTW, 356s have solid hull glass hulls to the waterline, cored above.

 

[JohnSn]

Thanks so much for all your input! It looks like there's a glass project in the future for this vessel if I purchase her.

It's clear that the added stringer will go under the shower pan. Any more details on the repair would be much appreciated.

 

[JohnSn]

Chuck,
You said that your vessel doesn't have the problem, but a vessel with a serial number one higher does have the problem. I'm guessing that the implication is that the problem was occasionally seen in production. I was hoping that would indicate that a fix was adopted by the factory at that HIN.
The vessel I'm considering is serial number 35249 direct from the HIN. What's the serial number of Eclipse?

 

[Bob R.]

We have Hull No. 231 and did not have the shower hull dimple problem. Our 356 was manufactured in April 2002.

 

[Jerry Clark H356 SV Persi]

Mine is Hull 296 and is a 2003 but was manufactured in fall of 2002, can’t remember which month. I’ve had it since new, bought in March 2003.

 

[Captain Larry-DH]

@Johnsn I don’t know anything about the “shower pan dimple” problem, not familiar with the boat in question, but the point loading issue from the lifting strap pin is NOT the same issue. (But you might have encountered both):

Any foam-cored fiberglass hull is subject to core crush compression damage from point loads, regardless of where the stringers are. A knowledgeable and careful yard crew knows that and will avoid point loads on a cored hull by whatever methods are appropriate under the circumstances.

 

[Don S/V ILLusion]

@Johnsn I don’t know anything about the “shower pan dimple” problem, not familiar with the boat in question, but the point loading issue from the lifting strap pin is NOT the same issue. (But you might have encountered both):

Any foam-cored fiberglass hull is subject to core crush compression damage from point loads, regardless of where the stringers are. A knowledgeable and careful yard crew knows that and will avoid point loads on a cored hull by whatever methods are appropriate under the circumstances.

What makes you think it is a cored hull?

Actually, this isn't a hull deformation problem as much as a faulty equipment problem in that no strap pins should exist in areas where they contact the hull.

 

[Bob R.]

The Hunter 356 does not have a cored hull below the water line. It is solid fiberglass below the water line, balsa cored above the water line. The shower pan section of the hull is well below the water line.

 

[Don S/V ILLusion]

The Hunter 356 does not have a cored hull below the water line. It is solid fiberglass below the water line, balsa cored above the water line. The shower pan section of the hull is well below the water line.

People come here primarily to seek advice or informed opinion. It's therefore important to ensure we point out incorrect assumptions.

 

[Captain Larry-DH]

snip
Actually, this isn't a hull deformation problem as much as a faulty equipment problem in that no strap pins should exist in areas where they contact the hull.

I made that point above. Not faulty equipment but faulty use or choices of equipment.

 

[Captain Larry-DH]

The Hunter 356 does not have a cored hull below the water line. It is solid fiberglass below the water line, balsa cored above the water line. The shower pan section of the hull is well below the water line.

Thanks for clarifying. I didn’t know that.
This info doesn’t change or invalidate anything I wrote above about cored hulls, or that the boat yard was incompetent or negligent for letting the pin be in hard contact with the hull.

 

[chuckwayne]

Escape is hull number 198, produced in spring 2002. My friends boat is number 199, probably went down the line the same day. It appears that the problem was a manufacturing issue - they may not have recognized the problem and implemented corrections - it's clearly a worker issue - for some time

 

[Franklin]

The hull is not the same thickness all the way around. My H376 is 1/2" thick on the sides below the water line, but 1 1/2" thick near the keel. Here in Tonga I had my boat hauled out by a trailor that was not the proper size for my boat. The support braces could not get all the way back to the bulkhead and the hull flexed in about 1/4". Nothing we could do about it so we just continued quickly. All is good though.

I second the fact that the pin should not be touching the hull at all.

 

[chuckwayne]

Franklin,
I agree - the pin should not be touching the hull at all. But that particular spot is a known mfg issue on some 356s. If the stinger is missing, the hull will deform there just with pressure from a jackstand

 

[JohnSn]

I asked my surveyor about the pin. He sees nearly 200 boats in a sling every year. The slings aren’t long enough to be able to move the pin so that it doesn’t contact the hull. It is possible to have the pin right in the center-where the hull is the thickest.

I’ll attach a picture as soon as I can.

I’ve decided to pass on this boat due to a different issue.

 

[Don S/V ILLusion]

I asked my surveyor about the pin. He sees nearly 200 boats in a sling every year. The slings aren’t long enough to be able to move the pin so that it doesn’t contact the hull. It is possible to have the pin right in the center-where the hull is the thickest.

I’ll attach a picture as soon as I can.

I’ve decided to pass on this boat due to a different issue.

Sling straps come in different lengths so yes, they can, however, a cynical view is that they bought cheap short ones causing the problem. Personally, I've seen some massive travel lifts and never seen a boat yard travel lift which depended on multiple straps pinned together.