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Water leak, not HDS?


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Got an 03 Sportster. Has HDS. Buddies borrowed it and hit a rock and ruined the prop. Not terrible but curled the ends up. Ok fine I replaced it but now I've got a really bad leak. Like 10gph. I've hand pumped it out and timed it. The water is coming in thru the hole in the stringer in front of the engine at the bilge pump. I immediately assume HDS, but I pump it dry and there is no water coming from the stern. The water in the bilge slowly rises until it reaches the mufflers and HDS box. I'm assuming this is single wall here so what I'm seeing is the box glassed right onto the hull and there is not a second layer under there aka the box has no bottom, it's just a hole in the hull that the prop shaft goes through? My trailer is 3 hours away so I can't readily pull it but I'm afraid to leave it. 

If I'm right about HDS where is the water coming in? Checked the plugs,  rudder, hull drain, etc. Does the HDS leak out underneath somewhere and it's a double hull in that area?

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Or it’s the HDS box.  Because it almost always is.  The water usually percolates up around the T handle drain area as it’s the lowest opening between the hulls.  But I agree, you need to check for damage at the fins and strut.

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So there is a double layer hull then? I see the T drain and think whelp the bilge is the bottom of the boat I guess? But you'd think there was two layers and foam. This is my first DD and I've never sawed one in half! My question was, would I see it coming out around the HDS box from the top by the mufflers or can it be leaking further down inside the box. I obviously can't pull the cover.

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I would start with the fins. They are attached with threaded screws. I’m not 100% so maybe someone who has replaced one can tell you, but I’m pretty sure they screw into a stringer up there somewhere.... start with the cheapest fix and work your way to the most expensive if your trying to diagnose... 

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Pretty sure on an 03 the tracking fins just screw into the fiberglass of the bottom of the boat, it is thicker there.  Start by seeing if they are all there, and don't show a sign of impact.  

If it isn't a tracking fin, its the HDS.  The HDS does not typically show you the leak directly, it is a glassed in item, that joins the main hull up near the thands drain, that's why waterleaks out there, plus that is actually the low spot in the boat at rest. (that is my general understanding of the HDS leak anyway.) It was probably ruptured by the force of the rock strike.  How fast was he going when it happened? and how long did he have to motor back ?


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Your buddies should be frantically combing the local area to borrow a trailer that your boat will fit on.  Please tell me they aren't home drinking beer while you take care of your sinking boat. 

The hull is single wall.  The most likely scenario is that the strike bumped the strut upward, flexing the hull and delaminating the HDS.  Not a difficult repair, but obviously you have to get the boat dry first. 

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The hull structure is single but the layer that forms the HDS enclosure and the pretty bilge is a second layer.  The HDS failure is the resin/thickener they use to join the two layers.  No, caulking the joint doesn't seem to work.

The correct repair, done by Farmers Fiberglass and I'm sure others, is to bond a new shaft log to the outer hull.  That's a grand.

There are threaded T nuts impeded in the hull and the fins bolt into that.  Replace bent strut and shaft, 3M 5200 the front fin.  Another Grand.

Ask me how I know.

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10 minutes ago, robtr8 said:

Gotcha.  Either way, it fails quite regularly. 

And it fails catastrophically.  "HDS - failing since 1996!"  :) (ed. note:  DUMBEST idea in a ski boat hull.  Ever.  Oh wait... the MC bolt on fins to stop chine lock on a crappy hull might have it beat).


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Ok last night at 6i was like screw this I'm getting the trailer! My friends were up visiting from Virginia so they were long gone. I think I thought the inside surface of the bilge pan under the mufflers was the very bottom of the hull but I guess not. Anyway, just got it up on the trailer. Zero sign of impact on hull or fins. Water coming out of the prop shaft hole even after 15 minutes so HDS it is. I should be able to repair this myself this winter if it's a matter of sealing and then adding a layer of glass in there. I'll know better when I pop the cover. 

Just pissed cause I was still skiing every day here and mornings the water is glass and no boats. Was going to pull it after next weekend so I guess it's not a huge loss but this weekend has been amazing and I spent it under the boat changing props with a snorkel (do not recommend) and driving 6 hours to get my trailer!

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12 minutes ago, Eagleboy99 said:

There are quite a few  pages detailing the fix.  Best is a shaft log though, but you can just glass the bejeepers out of it.

I like the looks of that little shaft log and that looks pretty easy to do. I think you could modify the design shown in the Everglass blog to cut the mold block to shape first and then you could add a bottom flange to the log to help with the initial adhesion to the hull, then glass over it. Feels better than lining the box and hoping the hydrostatic pressure doesn't lift it up again over time. 

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Just pulled the cover and filled the bilge. The good news is the HDS box has already been repaired. The bad news is they didn't pull the back two strut support bolts and glassed around/over them and that back seam is where it's coming in. Looks like the washers and bolt head moved and cracked the glass over top and it's either leaking around the bolts or under the repair. Honestly looks like it's coming from under the bolt head but I guess that's impossible in the trailer eh? Ha. So I think I just pull the 6 bolts out, lay a fresh piece of glass down across that whole area and up the back wall, redrill, and get back to it. It's all nice and clean in there already. Not sure why you'd leave those in to do the fix that's so easy to pop the bolts out?

The strut must be gasketed or something from below? What creates the seal around the bolts?

Video of water coming in:






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Probably 5200 adhesive for the strut.  One of the things to cosider is if there is damage between the layers.  Reglassing _should_ fix it, but I dunno.  As I also do not know why somoen would not have pulled the bolts, other than laziness.

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What seals the through bolts though? 5200 or 4200 etc under the head on the strut base, and then the base to the hull? Bolts into bottoms of boats is so weird ;)

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