Home	Major Hull Crack "Smile" Fracture in Stem

About eight years ago (roughly 1998) Jim Robinson's Pilot developed a leak which was traced to a crack in the hull, on the centerline, about 18" forward of the mast step. In 2006 similar cracks occurred in Kit Wiegman's Cassiopeia, Rich Shoenhair's Windwalker and Guy Dean's Dominique. Though someone dubbed the crack a "Smile" and the term is now recognized among San Francisco Bay area boatyards, this can be a major problem, and should be considered seriously. It is definitely not something to "smile" about.

In the 2007 Vallejo Race, on May 5th, the winner, Captain Hooke, arrived at the dock to find water to the floorboards, and has now confirmed that they are the 5th Islander to have gotten the "Smile" crack. They finished the race with heavy backstay tension beating into 30 knot gusts with full main and 135% genoa. She was hauled at Bay Marine, and her pictures and story are below.

The Smile occurs in the form of a transverse crack along the centerline of the hull just forward of the area where the hull begins its descent to join the keel - the inflection point from the curve coming down the bow to the curve down to the keel. It is developing in an open bay between floor frames which has slightly less strength than the surrounding surfaces. The cracks have been between 6 and 12 inches in length and have followed a layered migration in the cross sectional view resulting in the break appearing on the inside at a slightly displaced location from that on the exterior. In most I-36s this area of hull is not visible from the inside because of the cabin sole insert. However, any leak that develops in this location will travel to the water sump under the head and dribble into the forward bilge. It is wise to check to see if leakage from the head sump is fresh or salt water.

All of the four occurrences known to date have been repaired and the boats have been returned to their owners with full systems capability for safe and normal recreational use. For that matter, Pilot went on to win several more Season's Championships, Cassiopeia raced to Hawaii and sailed back (nasty ride!), and Windwalker came in second in the 2006 Nationals Regatta.

When the 2006 incidents first appeared, repair estimates from yards ranged up to $20,000. But Jock MacLean and Ken Keefe of KKMI took a systematic look at the problem and brought in Naval Architect Jim Antrim to study the problem. Despite his extensive experience, and the comments from the marine surveyors, no one single factor or consistent pattern has been singled out as having specifically caused this problem. Several possible elements may be involved and the greater the exposure to these stressors, the greater the potential a boat has to develop this problem. A partial list of their observations follows.

All four of these boats were sailed in the San Francisco Bay area and all four had been raced in the Bay's 20 - 30 knot winds at some time in their past, some quite aggressively. Back stay adjusters were utilized, and in one case possessed unusually strong mechanical advantage. All of the boats had struck or been struck by objects, though each occurrence was different than the others. At least one boat had the gel coat on the bottom removed for osmotic blister treatment without adding back reinforcing fiberglass, and if the outer layers of the original woven roving had been removed, it may have compromised the hull strength in that area. Think of a hard boiled egg with its shell removed. A degree of twisting moment from loose or delaminated bulkheads, including chainplates, has been listed as another possible factor and it's easy to imagine the degree of variability with respect to that scenario. Another variable thought capable of contributing to the problem is the random nature in which the lay up process was performed in the manufacture of these production line boats. The Islander 36 is as solidly built as any other competitively priced boat of its time, but the randomness of the pattern, size, and exact placement of the roving and application of the resin provides some speculation about possible strength variability from one hull to another. Yet another factor that is different for every boat from the day it is launched is the stress to which the hull is subjected from the pattern of wave impact.

Through the services of marine architect Jim Antrim and the professionals at the respected yards of Keefe, Kaplan Marine (KKMI), and Bay Marine, along with Kit Wiegman's personal job at Svendsen's, a guideline "fix" has been developed. For boats that have developed the crack, both the inside and outside of the hull have been strengthened. For boats that might feel they are vulnerable to a future crack, it is thought that the exterior fix could prevent one. KKMI estimates the exterior work at about $4,500 and both interior and exterior around $8,000 - all depending on specifics for each boat. Guy Dean paid a fee to Jim Antrim and had Bay Marine perform the interior and exterior repairs with about 45 hours of labor.

The pictures below show repairs done primarily by Kit Wiegman to Cassiopeia while at Svendsen's, repairs toWindwalker, and the repairs to Dominique by Steve Taft at Bay Marine. Two additional pictures of Art Fowler's Zenith are added to show how new fiberglass was added when she had her bottom stripped for a blister repair at Svendsen's.

While there are no quantified guidlines for rig tension - particularly since most boats have been modified to some degree since they were built - the following is quoted from a 1979 Owner's Manual: (Capitals are as they were in the original)

"UNDER NO CIRCUMSTANCES SHOULD ANY OF THE RIGGING BE SET UP AS TIGHT AS POSSIBLE. FOR ALL SAILING CONDITIONS, WE RECOMMEND THAT THE MAST BE EXACTLY VERTICLE AND IN THE COLUMN, WITH THE RIGGING "FIRM". IT IS VERY IMPORTANT THAT A KNOWLEDGEABLE PERSON WHO UNDERSTANDS THIS CONCEPT OVERSEES THE INITIAL TUNING OF THE MAST AND RIGGING. ... When racing, the backstay may be tightened to compensate for the extra forward loading applied by the Genoa. At the conclusion of the race it is very important to "slack off" the amount you "took up" on the backstay turnbuckle, as this avoids setting up unnecessary strains on the hull and rig. Too much tension on the backstay is probably the prime reason for mast and rigging failure. It has been found that tension in the backstay can increase 150% to 200% due to the wind load on the headsail and dynamic loading due to heavy seas. The tension on a shorud or stay should not exceed 25% to 30% of the cable's breaking strength at the outside limit. Below are the breaking strengths, in pounds, for 1 x 19 stainless steel wire as supplies by the factory: ... 9/32" = 10,300 lbs." (The spec size for the backstay.)

A complete copy of the Owners Manual is available on the Islander Blueprints CD. To request your copy: Islander Blueprints CD If any of our readers know of additional incidents and methods of repair, we would be happy to share them.

Links to these resources:

Antrim Associates	Jim Antrim	http://www.antrimdesign.com/composite/
KKMI	Jock MacLean or Ken Keefe	http://www.kkmi.com/
Bay Marine	Steve Taft	http://www.baymarineboatworks.com/
Svendsen's Boat Works	Sean Svendsen	http://www.svendsens.com/
Anderson's Boatyard	(-)	http://andersonsboatyard.net/

Pictures by Kit Wiegman, Guy Dean, Rich Shoenhair & Art Fowler. Click on images to enlarge, click "Back" to return.

- - - - - - - - - Windwalker - - - - - - - - - -
Rich Shoenhair

Rich had a temporary patch applied at Adnersons, then moved to KKMI where the enigneered fix was applied.

OrigCrackPortSide

OriginalCrackLookingUp

AndersonTempPatch

exterior PatchPort side	ExtPatchStarSide	ExtPatchPortSideLongView	ExtPatchStarLongView
InteriorRepair	interiorRepair2	NewSoleHatch
ShaftSupport

- - - - - - - - - Cassiopeia - - - - - - - - - -
Kit Wiegman

Kit did much of the work himself at Svendsen's. Note that Kit decided to remove all of the old floor frames back through the cabin and replace them, including adding a new floor to cabintop bulkhead at the aft side of the head. These repairs are not related to the Smile - but since he was planning on crossing the pacific, he went the whole nine yards.

Keel crack "Smile"	close up of crack	Port view	Length - starboard
length - port	Inside view	out with the floors (note - no liner)	Mast step removed
New G10 frames under mast step	New mast step completed	Main cabin floors	One-piece floor to cabin roof connection

- - - - - - - - - Dominique - - - - - - - - - -
Guy Dean

Dominique's work was done at Bay Marine by Steve Taft.

Interior set-up	Repair supplies	Interior prep	Limber hole tube
New forward frame	Glass going in	Interior repair	New floorboard ...
bottom side & ...	edge detail	Interior complete.	Exterior patch
Detail port	Feathered in	Detail starboard	Paint port
Paint starboard	Better than new!

- - - - - - - - - Captain Hooke - - - - - - - - - -
Tom Newton

Captain Hooke's work was done at Bay Marine.

During the Vallejo Race 2007 from Berkeley to Vallejo, the Captain Hooke sustained a smile crack. The repairs were undertaken at Bay Marine in Point Richmond and were completed in less than two weeks at a cost of $5600 with a total of 52 hours labor. The number of layers involved in the repair is unknown. Below are nine representative shots of the job before, during, and after.

Front view	Port side	Starboard	Inside before. The sump hose is obscured here by my finger, but this entire cavity has been filled with repair work.
Ground port	Starboard ground	Starboard side patch	Inside after. Note: in the top left, the sump to bilge hose has glass up to its bottom. This represents at least one inch of glass repair work I don't know how many layers.
Inspection cover

- - - - - - - - - Zenith - - - - - - - - - -

Art Fowler

Zenith's work was done at Svendsen's.

Zenith peel & glass addition

Layered detail.

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