Hobie repairs begin in earnest

I’ve been moving tentatively on the hull repairs for the Hobie 16 because it’s scary. Grinding down gelcoat and fiberglass generates clouds of hazardous dust. There’s the expense of buying all the epoxy product to do the repair, not to mention the associated footprint.  It’s not clear how much trouble I’m getting into. The issues seem manageable but then I’ve had limited fiberglass and no boat repair experience. Finally, there’s the possibility of screwing up and either 1) compromising the structural integrity of the hulls or 2) not getting done in time. We had to scrub Hawaii, Around Lake Michigan is scheduled to begin after Whirlwind delivers the new sails, no later than August 7 +/- 1 day.

A crack in the gelcoat? NOT!

A 'crack' in the gelcoat - NOT!

In the past couple of weeks I researched repair techniques, upgraded and acquired tools and finally ordered or picked up most of the materials. With all this afoot I forgot about the sailing rockstar that I am collaborating with and the whole point of blogging. Kai has done all kinds of crazy repairs, he’s a wealth of knowledge. The rest of you can’t taste the intensity of the moment unless I am posting my process. So, without further eloquence – restoration!

Significant delamination with spacetime distortion, (note curved ruler).

Significant delamination with spacetime distortion, (note curved ruler).

After grinding some of the problem areas on the starboard hull I was less reluctant to investigate a crack on the port hull. With a precision screwdriver, I pried gently at the edge of the crack and popped off a chunk of fiberglass, exposing the foam core. Significant delamination!

Here’s a super quick tutorial. Cloth woven from glass fiber is saturated with a mixture of liquid resin and hardener. The resin and hardener react chemically (cure) to form a rigid and super tough plastic.

The sides and tops of the Hobie’s hulls have a sandwich construction –  a layer of foam between two thin layers of fiberglass.


This double skin make Hobie hulls strong. The outer fiberglass skin is coated with gelcoat, another curing mixture sans fibers that acts like a thick paint.

A famous feature of Hobie cats is that they can be sailed up onto the beach. For single hulled boats with keels that’s usually a disaster. Younger sailors skid their Hobies out of the water and on the sand at high speed, I know I did. As a result the bottoms of Hobie hulls can get pretty scraped up, especially if the beaches they sailed up onto were rocky.

Hard impacts either on land or water can also break the fiberglass. In the cleaning and inspection post I posted an image of damage to the starboard hull’s stern, probably from a trailer mishap.

Even a gently handled and accident free Hobie hull can have problems. When the fiberglass is initially cured, not all of the resin and hardener reacts, leaving tiny pockets of liquid in the cured material. Water can migrate into these pockets and get trapped, forming acids which eat away at surrounding solid. Eventually so much water gets trapped and the surrounding material is so weakened that it bulges out, ripping apart the sandwich. This is called delamination. The crack in the above photo may have started as an impact left unrepaired.

Let’s backtrack a bit and set the stage. This is a major physicality moment, let’s savor it.

The garage wasn’t too cluttered until I showed up in May with 20 boxes of crap from Brooklyn. Though daunting I processed it all, even locating a recycling company to pick up the styrene from all the old computer boxes I had in storage. With the decks cleared for action, I could strategize on the mess that restoration would generate. Rather than cover the entire inside of the garage with plastic, I decided to build an isolation tent with my favorite hex pipe system – I call it LEGOs for adults. $200+ for 60 ft of galvanized 1-1/4 inch pipe, not to mention the hex connectors which I always keep in stock, probably another $60. Add another $10 for some heavy plastic I had stashed away and some duct tape.

Galvanized pipes and the port hull
Cleared for action
Cleared for action
Starboard hull in the tanning booth
Starboard hull in the tanning booth

The cleaning and inspection yielded some interesting issues. The top row of pictures are likely just cosmetic patching the gelcoat though some fiberglass might have to be removed and replaced if it’s been damaged.

Scrapes near the bow, from beaching on stones
hull bottom near bow shows glass, lots of fast beaching
Exposed fiberglass and gelcoat scrapes
hull bottom with horizontal gel coat scrapes
Bow - first contact when sailing onto beach
Bow – first contact when sailing onto beach
A crack in the gelcoat? NOT!
A crack in the gelcoat? NOT!
This dark spot has a drip stain running out - acid?
This dark spot has a drip stain running out – acid?
Flipped near stern, gelcoat chunk mysteriously missing
Flipped near stern, gelcoat chunk mysteriously missing

The second row are more sinister issues. The left most picture is a repeat of the bulging crack before I popped off the delaminated fiberglass. The second is an impact mark with a discolored drip stain running out of it. Could this be the action of acid formed from trapped water? If so the damage is likely to be far more than the crayon indicates. The third is from the stern of the starboard hull, a big chuck of gelcoat is missing and the fiberglass is exposed, but there doesn’t seem to be any impact trama nearby. Recalling the trailer accident, this gelcoat could have been poorly bonded and popped off during the impact that broke the glass around the rudder. That’s not the half of it. After inverting the starboard hull on horses in the garage, water began weeping out of the gelcoat hole. After two weeks of sitting high and dry, I found a little puddle there this morning!

The water puddle extends to the left of the arrow.
It’s hard to see, but the brown stain is standing water seeping out of the hole. It’s dry everywhere else. The water is coming from UNDER the gelcoat. BAD.

To put all this into context, here’s a clever shot of me looking competent. One can hardly tell that I’m holding the camera with the other hand. The point is that I’ll need this boat to be structurally bulletproof before I take her out for 1000 miles of fun on the big lake. My life might depend on getting this right… whee!

My life depends on this

Here’s some shots of the excavations.

There's wood underneath

There's wood underneath

A gelcoat ding goes deep

A gelcoat ding goes deep

A nickle size hole in the outer glass and foam. The inner skin feels solid.

Removed outer glass and foam. The inner skin feels solid.

Checking glass along the bottom

Checking glass structure where bottom was scraped.

Borrowed my brother's Fordham with footswitch, sweet!

Borrowed my brother's Fordham with footswitch, sweet!

Art shot of bow jutting out of the tent

Art shot of bow jutting out of the tent. Gotta dig the Century Optics wide angle.

So back to it, more pictures as events unfold.

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4 Responses to Hobie repairs begin in earnest

  1. Kai says:

    Hey Dan, don’t be scared of it! Just make sure you sand back the gel coat for the new fiberglass to have plenty of surface area to bond with. Use a syringe to inject some resin between the foam and loose fiberglass. Also make sure you mix the resin parts correctly or it will set too fast or not at all. Lastly, have fun with feathering out the patched area. I wouldn’t worry about it being perfect (it never is unless you’ve been doing it for 20 years). As long as it’s sound and solid it’s all good. Cheers! ~Kai

  2. Kai says:

    There’s something disturbing about the tanning booth picture. Looks kinda like Mr. Visqueen Square Pants sporting a hobie hull woody. 😉 ~K

    p.s. I notice that these hulls are asymmetrical, as are ‘Desire’s keels. Does the curvier side face in or out?

  3. Dan says:

    Curvy parts face each other, the stripes face out. Speaking of penises, if I put my two 16’s end to end, I’ve got a 32 footer. Desire is only 26 feet…

  4. Kai says:

    Well I’m sure you are aware that it’s not really size that matters, it’s what you do with it…

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