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What to Check After Hitting Sandbar


albernhagen

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Hey All,  I hit a sandbar yesterday at about 20mph yesterday due to me thinking I knew a spot on the water that I was misremembering.  This was in a 2012 Response LX.  it was a very soft/sandy bottom, but we did have to unload the boat to slowly push it off the sandbar and into deeper water.  What all should I check to make sure I didn't damage anything?  We didn't notice any vibration.  My buddy thought he felt it a little bit at WOT, but I didn't notice any.  It has a brass 3 blade prop, and the prop appears to look 100% fine -- no noticeable bends or nicks.  Shaft spins easily by hand so it seems okay, but wondering if I should measure it.  The tracking fins all look dead straight and fine.  We have to fix the engine cover as people in the back slid into it and it pulled the screws out of the fiberglass, but that should be simple to fix.

I don't know the standard RPMs for this boat either.  What should it be turning at 36mph?  I can double check that it's still going the proper speeds and R's.

Thanks!

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Sounds like you got away with this one!

No so for me and the rock bar I hit yesterday at idle speed.  Clunk, clunk, sh!#!!!

No other boats around so I stripped and dove under the boat to feel 2 bent prop blades.  Slow slow (did I say slow) back to the lift to put the spare on.  Everything else under there looked fine.  Boat ran fine - actually better for cruising than before since the spare is a 16 pitch and we were lightly loaded.  Dropping "surf" prop off at Prop MD.  $125 :Frustrated:

Got me thinking: Wouldn't a variable pitch prop be nice?

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1 hour ago, albernhagen said:

Hey All,  I hit a sandbar yesterday at about 20mph yesterday due to me thinking I knew a spot on the water that I was misremembering.  This was in a 2012 Response LX.  it was a very soft/sandy bottom, but we did have to unload the boat to slowly push it off the sandbar and into deeper water.  What all should I check to make sure I didn't damage anything?  We didn't notice any vibration.  My buddy thought he felt it a little bit at WOT, but I didn't notice any.  It has a brass 3 blade prop, and the prop appears to look 100% fine -- no noticeable bends or nicks.  Shaft spins easily by hand so it seems okay, but wondering if I should measure it.  The tracking fins all look dead straight and fine.  We have to fix the engine cover as people in the back slid into it and it pulled the screws out of the fiberglass, but that should be simple to fix.

I don't know the standard RPMs for this boat either.  What should it be turning at 36mph?  I can double check that it's still going the proper speeds and R's.

Thanks!

http://www.themalibucrew.com/_files/engines/indmar_2012_2015.pdf

WOT: 4600-5200MPH  or 5200-5600 based on engine.

Easiest way to check shaft and prop is tape a piece of wire really close to shaft. Spin by hand and see if the distance changes. Do the same thing with prop.

 

 

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Shaft is usually hard to bend. But the method above is a good way to have cheap reassurance.

I would check the strut to make sure it's straight up and down, it's brass and would be more likely to give than the shaft, then check the shaft alignment at the back of the trans where the coupling is. I would also give the rudder a good once over. The slight WOT vibration can be caused by the slightest, imperceptible variation in the tip of the one of the three blades - or if the shaft is out of alignment by .008 of an inch. 

 

Also check the skegs/tracking fins and make sure there aren't any gel stress cracks/fractures and that it's not leaking from around them on the inside.

Thankfully sand bars are way more forgiving than some other things you can hit. Like... logs or rock bottoms. Also thankfully the brass running gear gives way more easily, which prevents significant damage further up the drivetrain to more expensive things. Like transmissions.

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When you check the rudder you should have the same distance between the top of the rudder and bottom of the rudder hub in the hull, through its full radius of movement. You will be able to tell pretty easily if the stainless rudder shaft is bent or the rudder itself is bent. Surprisingly, the 1" shaft will bend before the rudder will!

Edited by wdr
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Bummer!

On the screws, I had a similar situation, mine were just getting stripped out.  I went to Joanne Fabric and wandered around.  Found some disposable little 1oz tubes that had unscrewable caps with a pointy end on them, trim to fit, like the end of a caulk tube.  I drilled out the holes a little bigger and trimmed off the carpet around them.  Trimmed off the end of the tube cap.  Then I poured 1oz of fiberglass resin in the tube, and added the hardener.  Then squirted the resin into the each of the holes.  Had to slowly squirt it in, several times, working my way around to each hole until they were all full.  Then it set up, and I redrilled the holes.  That method worked really well.

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Insurance might cover your repair if needed. My buds boat hit a sandbar while I was footing off the boom. Came to a complete stop in 1 second and I'm just standing in shin deep water looking at him. His shaft and strut were damaged. Insurance covered it and a new prop.

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Thanks all for the great information, I really appreciate it!

I had a buddy that had the measuring dial for the shaft and everything looks fine there.  We see no cracks or spiderwebbing anywhere underneath the boat.  The front 3 tracking fins look great and are dead straight.  We didn't measure alignment, but considering that everything looks straight and move smoothly, we figured it's okay.  The strut seems fine -- any ideas as to how that could be checked too, or is the shaft alignment the only way to tell?  I'll try and look at the rudder tonight to see if I notice any bend in it.

Seems like we got really, really lucky hitting a soft, sandy bottom in 1ft of water.  I'm going to have the prop checked and rebalanced just for peace of mind.  The prop itself looks perfect, but who knows if there's a slight bend that I can't see.  The fact that that is as straight as it is makes me think the rest of the components are okay, since I just have the brass acme 525 and would have expected that to be the first thing to really bend.

Thanks again!

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