Hunter 23.5 Hull Construction

[charlieyacht]

Keep hearing about balsa core. Just recently removed two hull transducers that were located under the aft berth just aft of the end of the water tank. The holes were tapered from the outside then relaminated, a little filling from the inside, a sanding and a few layers of mat and unwoven roving from the inside of the hull. Never did see any balsa core. All the constructions seems to be solid glass or maybe some coremat. Removed the hullside bilge pump thruhull and none there either.

Hunter service also said they didn't remember any balsa in the 23.5. Just don't personally like the stuff but if you have it you must be extra carefull.

How about the deck what is the reinforcement? One 23.5 I looked at did have a spongy deck near the jib sheet blocks.

After the transducers, took out the corresponding instruments and relaminated the cockpit bulkhead near the slatboards. No balsa there either. Any comments.

 

[Barnacle Bill]

End-grain Balsa core is the cheapest and strongest material used for lamination of cored decks or hulls, but there are different types. One of the best is Baltec's AL/600 which is coated and each square has resin so that moisture migration is minimized if penetrated with water (say from an improperly installed through hull or deck fitting). But, the key to successful core construction is vacuum-bagging which removes air from the lamination. There are other lamination techniques such as SCRIMP, which was developed by Bill Seaman long ago. It is a resin injected, vacuum bag assisted sytem where resin is delivered in a carefully measured method so that the resin to cloth ratio is consistent where there is no waste of either material, yadayadya. So, I don't think the Hunter 23.5 has a cored hull, but I could be wrong. The deck probably is. The old Hunter 22 was cored and the lamination was so bad that if you picked the hull up with straps in a basket pick with slings, it left a depression in the hull. Not good. A good lamination with balsa core will not alter the hull shape. But, regardless of what type of core material is used and especially with balsa, when installing a through hull, one must cut out the core material in a circumference larger than the thru-hull leaving the exterior fiberglass lamination in tact. Then the depression is filled with solid fiberglass the thickness of the hull so that you drill the hole that fits the thru hull size perfectly through solid glass and not the original core, which will eliminate any moisture migration into the rest of the hull. Make sense?

 

[charlieyacht]

Thanks for your thoughts on balsa. I watched boats being built with the stuff for 30 years at some good builders. Bottom line is no one except people like Viking and Sea Ray use it anymore. Everyone has pretty much gone to closed cell foams like Klegecell, Divinycell. I had a J30 which was balsa cored and those frp skins are pretty thin and that balsa pretty dry. Anyways it really doesn't matter but if you have ever dug out a bunch of mush that was once balsa core you probably feel the same way. It was just that I couldn't find any balsa anywhere but an early test mentioned balsa core and a post on a burst water tank on a 23.5 also mentioned it.

 

[Crazy Dave Condon]

I was the one who pushed for the 23.5 and first introduced the boat. There is no balsa core in this boat. The bottom of the hull is fiberglass with some dyvanacell in the sides. No wood coring or balsa in the deck either.

When laying any glass, it is always good to get the air out. You can use a brush by dipping constantly into acetone and patting down. Just make sure you shake the brush after dipping. Or the easiest way is to get a "RESIN ROLLER" which there are three and you can get them from West Marine. Makes life a whole lot easier getting air bubbles out.

Crazy Dave Condon

 

[av8erdunn]

I was the one who pushed for the 23.5 and first introduced the boat. There is no balsa core in this boat. The bottom of the hull is fiberglass with some dyvanacell in the sides. No wood coring or balsa in the deck either.

When laying any glass, it is always good to get the air out. You can use a brush by dipping constantly into acetone and patting down. Just make sure you shake the brush after dipping. Or the easiest way is to get a "RESIN ROLLER" which there are three and you can get them from West Marine. Makes life a whole lot easier getting air bubbles out.

Crazy Dave Condon

Dave,
Dou you have any thoughts on this http://forums.hunter.sailboatowners.com/showthread.php?t=114792

I was curious after reading your post. It is regarding balsa in the 23.5 hull.

 

[charlieyacht]

Scott said he would try to look for pictures of the damage. Check back. I've seen a lot of balsa core used. If the hull is cored then it is all the hull. Sometimes they only use it in the hullsides above the water line. Sometimes only in the deck areas. I took out two transducers in the 23.5 under the middle of the aft berth just behind the aft end of the tank and there was no core of any kind in that part of the hull. No core in the hullsides around the anchor well drain and the bilge pump outlet; took both fittings out. Relaminated the holes in the cockpit forward bulkhead where the speedo and depht gauge had been and no core there either. You can miss some coremat maybe but not chunks of balsa. Can't figure what good it would do only in the tank area anyways.

 

[Crazy Dave Condon]

I am surpised as I use to watch them make the hulls in the laminating shop. Never saw balsa being used in the hulls. Dyvancell which is a foam sandwitch material (not balsa) was used in the sides of the hull for light wieght, strength which shrinks when the resin hits it.

In additon, I have repaired many of these hulls and never saw balsa. I hope this answers that.

However, Hunter in the past did use marine ply ( cut in squares) in some hulls for strength but never balsa. Balsa I have seen used in the decks many years ago but not now with straight grain. The orginal balsa was a straight grain and if water penetrated into it, it would follow the grain. Marine Mfgs. later used cross end balsa to stop water migration if penetration occured.

Crazy Dave

 

[sesmith]

I emailed Hunter a year or so ago and asked about balsa in the 23.5. They said on some of the early 23.5's they added balsa only in the areas where the trailer bunks support the boat. This was later replaced w solid fiberglass.

 

[charlieyacht]

Now that could answer all the questions. Mine is hull no. 2293 and it's a '93 model built in '93. Don't know when they started but balsa is pretty easy to see and I haven't seen any.

 

[Crazy Dave Condon]

I never experience the balsa core but I may be wrong. Anyway you are good to go with your boat as it is fiberglass. the 23.5 was first test sailed by the public 8/15/91

crazy dave condon

 

[Barnacle Bill]

I beg to differ with Charlie Yacht. There are a lot of sailboat companies using balsa core in their hulls and decks. J/Boats is one, but many of their boats have used the SCRIMP resin infusion, vacuum-bag assisted method of layup.

 

[Crazy Dave Condon]

Barnicle Bill;

First, I was the one whom you can say got Hunter to build the 23/.5, 19, 26, 240 and 260 boats. I introduced each one and outsold and worked on them more than anyone else in the country. But above all, I watched Hunter employees build the boats and that sir very few have the experience and knowledge of that. So what I say is based on knowledge and experience specifically relating to the boats above.

Charlieyacht is correct that his boat was not the first as the very first boat was introduced and test sailed by the public starting August 15, 1991 as I was the one who introduced this boat. His was the second year of the boat in production based on the hull number even though he is off a little on his hull number. His hull is solid fiberglass.

kCrazy dave condon

Crazy Dave Condon