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  #1   IP: 172.4.223.233
Old 07-02-2019, 07:27 PM
Sailon1 Sailon1 is offline
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Serious Stern Squat

My Pearson 30 has some pretty serious squat-more so this season for some reason. Stern drops about a foot at 5 mph with Atomic 4 running, and exhaust is under water. Another issue that may be related is that top engine
speed is only 5 mph compared to 6.5 on better days.

Just wondering if anyone has similar situation? Could there be other reasons for the squat . . . issues with the prop or shaft?

The bottom has a fresh coat of paint this season.

Will the submerged exhaust cause damage? The A-4 has a non-return valve
in the exhaust, so that should help, and it looks like a steep angle for any water
to climb up the exhaust and beyond.

Thanks for your comments!
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  #2   IP: 32.211.28.40
Old 07-02-2019, 08:07 PM
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Al Schober Al Schober is offline
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I wouldn't worry about submerging the exhaust a bit. My Tartan 30 had the exhaust out the port side at the waterline, and would motor sail quite happily on stbd tack.
I'm curious about the stern squat. More bow/stern wave & slower speed is a sign of a heavy boat. How many drums of bottom paint did you apply? Seriously, how are you measuring speed? Is this GPS speed or is it a calibrated knotmeter measuring true speed through the water (BIG difference)?
It would also be nice to know what you have for a propeller and what you're reading on your tachometer.
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  #3   IP: 172.4.223.233
Old 07-05-2019, 04:18 PM
Sailon1 Sailon1 is offline
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Thanks for the reply. So far, I'm measuring on an uncalibrated wheel, and I don't have a tach--yet. I'll check the speed again using GPS.

I did take a closer look at the exhaust hose and it takes a steep climb up from
the exhaust pipe, over 2 feet, so the chances of any water backing up to the engine is negligible.

The carb hasn't been cleaned for at least 4 years (don't know if the PO cleaned it) so I will clean it ASAP.

thanks again
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  #4   IP: 74.88.0.97
Old 07-05-2019, 08:42 PM
nyvoyager nyvoyager is offline
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Sailon1 I sail a P30 #840...well not this year but that's another story.
My boat powers on it's lines. If your exhaust port is in the same position on the stern - that is a lot of stern in the water.
Something must have changed
I don't want to sound stupid but - Bilge is empty of water?
Did you add or move anything - something changed
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  #5   IP: 172.4.223.233
Old 07-07-2019, 06:20 PM
Sailon1 Sailon1 is offline
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That's the mystery, at this point. What has changed? Nothing unusual as far as I can tell. I did see a post (on Cruiser's Forum) about a saturated rudder possible causing a boat to squat. Possible fix is to drill 1/8 hole in bottom of rudder (or in keel?) and see if water drains. It seems that it would take a lot of water in the rudder to cause squat.

In any case, I'll give that a try at the end of the season when the boat is on its cradle.

Meanwhile, I can run at 4 mph without too much stern dipping down.

Thanks for the reply!


Quote:
Originally Posted by nyvoyager View Post
Sailon1 I sail a P30 #840...well not this year but that's another story.
My boat powers on it's lines. If your exhaust port is in the same position on the stern - that is a lot of stern in the water.
Something must have changed
I don't want to sound stupid but - Bilge is empty of water?
Did you add or move anything - something changed
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  #6   IP: 207.118.20.35
Old 07-22-2019, 07:56 PM
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capnward capnward is offline
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Is it stern squat, or stern wave? It's normal for a displacement sailboat at speed to have water rise up near the stern. I know that when my boat (which is about 1500 pounds heavier than designed) gets moving fast, there is a quarter wave near the transom that you can easily reach out and touch, less so on the windward side. At hull speed, which is about 6.5 knots, it looks like it might come up on the deck. My A4 cannot quite reach hull speed, so this happens sailing occasionally. The exhaust outlet in the counter under the transom is definitely underwater then, with no ill effects. There is a gate valve in the exhaust near the outlet to keep salt water out of the exhaust in a following sea, but I have never closed it. The exhaust hose goes up at least 2 feet, just under the cockpit seat, before it drops down to the engine. I have stern squat when there are 6 adults in the cockpit, and the water tank in the bow is empty. Makes it harder to sail to windward, or maneuver in tight spaces, but not a big problem.
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Old 07-22-2019, 08:01 PM
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