SJ23 Tech Tip FAQs, (Updated 2002-04-03, Bob Schimmel)

General Info and Things to Watch for When Buying a SJ23.

Thinking of buying a San Juan 23 sailboat?  Some hulls out there are in excellent shape and require only cleaning and waxing. The first hull came out of the mold in 1972 and most of them are still in good to really good condition.  This is because back in the early days of fibreglass boats, the designers hadn't figured out how to calculate the strength of the material.  So to be safe they built the hulls with the same thinking as if it was a wood hull.  This lead to over building a fibreglass hull.  They were heavier and stronger than required, exceeding many of today's hulls.  However, ALL hulls require some sort of "fixing" because I have yet to meet a sailor who didn't want to change something!  This is half the fun of boating, but I digress. 

Brief History - "The boats were named after the San Juan Islands in the Pacific North West.  The original boats were built by Clark Boat Co. at their main factory in Auburn, Washington with another one slightly later in New Burn, North Carolina.  The Clark brothers built their first boat in the early 1970s and their last one in 1980.  After that, various other companies (I've heard of two) built them until 1984.  A brochure from the later companies will state, "built by San Juan Sailboats."  That's one way of telling the difference.  Regardless of the company owner, all the hulls came out of the same original mold.  I'm not a surveyor but I've inspected some boats built by San Juan Sailboats and I can't say they are inferior or superior to those built by Clark Boat Co.  I've sailed on both and found no difference.  They don't oil can.  In closing I can say that A San Juan 23 these days has depreciated to the point that it should not loose value. The value should be stable as long as it is kept in good condition." Gene Adams.    More History

The Appeal - What's amazing is that San Juan sailboats are still popular today, after so many years.  It almost seems like the popularity is on the rise.  The boats are in demand because they look good.  They have very nice flowing lines that you simply don't get tired of looking at, either at anchor or under sail.  The real plus is they GO like the wind!!  There is no other 23-foot sailboat that offers as much sailing performance and room for the low cost. 

Understanding the Hull Serial Number - The serial number is imbedded in the transom, above the outboard engine mount.  The following example is from Hal Mueller's boat; OLKJ 0223M78E. 
"I believe the OLKJ is the manufacturer's identity code. 0223 is the hull number and M78 means it was manufactured in 1978 (I think the E tells you the month).  This is consistent with my boat."
Hal Mueller. 

Sail Number - I have no idea how Clark picked the sail number for a hull.  I can only assume he started at 1 and went up from there.  If that is the case Panache at #109 is one of the original hulls and shows no sign of fatigue in 2023. 

General Construction - The hull is hand laid polyester resin.  The keel is lead shot and resin poured into the keel stub.  The deck and cockpit hatches are balsa core.  The hull/deck joint (Tech Tip B16) is glued and bolted with an aluminum toe rail.  See Tech Tip H07 for the keel design.

SJ23 Review 1986 & Review 2013.


Things to Look out for - Fortunately the SJ23 suffers from no major design problems.  But time has a way of finding a weakness, even in the best of designs, especially if the boat was abused through poor storage or maintenance.  The following points are listed to help you with your decision.
  • Corroded Centerboard Hardware - Corrosion eventually happens to all metal parts located below the water line, regardless of the manufacturer.  I receive way more many queries from salt water sailors than from fresh water.  See Tech Tip B01 for a repair procedure.
  • Deck Leak & Bulkhead Stains at Chain Plate - This problem is almost always caused by not loosening the shroud turnbuckles while stepping the mast.  Check the bulkheads for water stains below the chain plates.  In an advanced case, check for wood rot at the bottom of the bulkhead.  Occasionally the fibreglass at the bottom of the bulkhead has weakened so this should be checked for an integral bond of the bulkhead to the  hull.  See Tech Tip B07 for a repair procedure.

    - The rest of the points are in no particular order but should be checked just the same.
  • Cockpit Locker Lid Leaking - This might be the only weak design point in a San Juan, regardless of the model.  The lid design is prone to leaking along the back when heeled and maybe delaminating because it is not supported from below along the hinges.  It also has lots to do with abuse by the operator.  See Tech Tip B15 for a repair procedure.
  • Bow Cap - The bow cap is not sealed to the deck as well as it could be.  This is more of an assembly problem than anything else.  It will eventually leak as it may receive a considerable amount of damage through abuse over the years.  After all, it is the pointy end of the ship and likely gets shoved into a dock or two during its life.  The cap can easily be replaced and holes can be sealed.  See Tech Tip B12 for a procedure. 
  • Delaminated Deck Core - This has more to do with bad hardware installation by the owner than by poor manufacturing.  The single biggest source of this problem is water absorption through a unsealed hole drilled in the deck.  This usually happens if a fitting screw leaks or if the deck is damaged.  Storing the boat in the hot sun will deteriorate a laminate quickly and so will continued jumping on a damaged area.  See Tech Tip G08 for a repair procedure.  There are few, if any, microscopic holes in the gel coat. 
  • Fatigue Cracks on the Transom - If the boat has a one-piece rudder then check for stress cracks around the gudgeons on the transom and check for fatigue cracks around the pintle bolts on the rudder.  Damage could be the result of the rudder accidentally 'touching' the bottom.  (This problem is definitely associated with abuse by the owner.  Unfortunately the hull bears the scars).  For this reason it is wise to inspect the transom of any boat before buying it. 
  • Rudder Blade - Check for fatigue cracks around any bolt that goes through the rudder.  In the case of a kick up rudder, check the blade around the bottom of the aluminum plates that form the hinge of the pivot.  See Tech Tip B09.
  • Fatigue Cracks at the Bottom of the Table Pedestal - As the center board is lifted the fibreglass may bend up, causing the gel coat to crack.  This is symptomatic of an air gap under the hull liner just aft of the table pedestal.  It is only a cosmetic problem.  See Tech Tip H07 for a repair procedure.
  • Hull Fatigue (Delaminating) at the Trailer Pads or Rollers - I hear about this problem every once in a while, thankfully not very often.  Mostly from boats that have been poorly placed on a trailer and stored for a "zillion years" in a barn somewhere.  The symptoms are a mushy hull with a definite soft depression in the area of the rollers or small support pads.  This problem is more associated with the boat owner than the design of the boat as it is due to poor placement of the trailer support pads, the pads are too small or the boat was not squarely placed on the trailer pads.  Rollers, while convenient for launching, are generally too few or too small to adequately support a fully loaded sail boat.  The pounds per square inch loading of rollers is too high to consider them adequate for supporting a displacement hull.  Sometimes you see a hull that sits so crooked on a trailer that you have to wonder about who loaded the boat or why this job was done so sloppy.  It just looks pitiful and it's such a shame to abuse a good craft like a San Juan sail boat.
  • Gel Coat Cracks Due to None-uniform Support from the Trailer - This problem has to do with support pads that are poorly aligned to the hull resulting in too much hull weight resting on the keel.  If the hull is supported like this for too long or the boat is bounced over a rough road, the hull adjacent to the keel will flex and crack the gel coat on the cabin floor.  The hull weight must be uniformly distributed over the support pads and the keel must support itself.  I've only seen one boat like this and it didn't suffer structural weakness.  See Tech Tip A05 for a repair procedure.

Don't be afraid to tackle one of the jobs listed above.  They are within the capability of most "most carpenters with opposing thumbs".  Most questions are already answered in a Tech Tip.  If you still can't figure it out, cruise through the archived questions or sign up to the distribution list and let your questions fly.  There are lots of sympathetic ears out there willing to help you.  I suppose you could also email me!  Good Luck Bob Schimmel.


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