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-   -   Hull water slapping (http://www.trawlerforum.com/forums/s3/hull-water-slapping-13881.html)

Bohans 02-24-2014 05:43 AM

Hull water slapping
 
At my marina where i am permanently moored and living on our boat, a 60 foot Maritimo convertible is next to us. I am amazed at the degree of hull water slapping against all the shines the whole way down its length. It is so loud, that is sounds as though a bilge pump is permanently on sucking water and gurgling away. I find it hard to believe anyone could actually sleep inside the boat due to this loud noise.

Does anyone else have this issue with hulls that slap badly. Surely this would be something the designers would test for? For me, what a waste of $2M on a boat so poorly designed it has this undesirable feature.

Our boat is so quiet, even with some wind waves (of which there are none right now and the noise is stillgoing). Our hull was designed by NA Howard Apollonio and i guess there is no substitute for good hull design.

Any thought?

Hendo78 02-24-2014 07:18 AM

Quote:

Originally Posted by Bohans (Post 215492)



Any thought?


Ear plugs :ermm:

Ski in NC 02-24-2014 07:46 AM

Planing hulls need some sort of spray rail or reverse angle on the chine to deflect water outward and slightly downward when running. Otherwise the water ends up all over the topsides when running. The downside is they slap and make noise.

rwidman 02-24-2014 07:47 AM

Every boat is a compromise. It's easy to criticize someone else's boat but what might the owner of that boat be thinking about your boat?

If the noise is really bothering you, ask for a different slip.

Shrew 02-24-2014 09:02 AM

Quote:

Originally Posted by Ski in NC (Post 215515)
Planing hulls need some sort of spray rail or reverse angle on the chine to deflect water outward and slightly downward when running. Otherwise the water ends up all over the topsides when running. The downside is they slap and make noise.

The reverse chine on a planing hull is not to reduce spray. It is there to dig in and allow the boat to hold a line in a turn. Otherwise, the hull could start to slip in the turn. This is not necessary in semi-displacement hulls.

Yes, it will 'bang' on the inside as the chine and wave hit. Sometimes a 'cupping' effect can occur that is loud. For the first year we had our express cruiser, it would sometimes sound like water 'glugging' in like a ruptured hose.

After a while it becomes another calming sound of boat life, like waves crashing on the beach outside of a seaside cottage.

sunchaser 02-24-2014 09:37 AM

People pay millions to have a beach house with crashing noisy surf. People also pay millions to have a fast yacht that can safely turn. Noise reduction at rest for these vessels pales in comparison to having huge speakers at 115 dba playing Gaga's latest. Consider yourself lucky that all you hear is a hull slap.

Ahab7 02-24-2014 09:44 AM

Scottsdale AR

sunchaser 02-24-2014 09:48 AM

Quote:

Originally Posted by Ahab7 (Post 215554)
Scottsdale AR

Morris Plains ND ;)

Ahab7 02-24-2014 10:25 AM

Excellent response! Love a quick wit! Looking forward to the sound of the snow finally melting and dripping off our roof.

Richard W 02-24-2014 10:57 AM

Here you go ... not your roof but something to look forward to:

the sound of snow melting - YouTube

bligh 02-24-2014 11:11 AM

The nordic tug 42 we chartered last year had slap from the chines. My father in law described the sound in the fo'csle as deafening while sleeping up there. Definitely more of a design flaw than a 'compromise'.

Ski in NC 02-24-2014 11:28 AM

Mine slaps BAD too. Worse in the v-berth as that is where the rails meet the water line. Worse in calm anchorages where there is just a little wind ripple, like one inch waves!! In a few cases I put a "monkey line" (Carolina term!!) on the anchor rode and pulled around to the transom, so boat hung ass-first into the 1" chop. That solves the problem. Looks funny, for sure. If it gets rough, just throw the monkey line off and boat goes back to hanging by the bow.

bligh 02-24-2014 11:53 AM

I find it amusing that yacht builders have people convinced that 'master' cabins in the fo'c'sle are a good thing. When I worked on a tall ship, you started out as a peon and had to sleep in the fo'c'sle, where, when under way, you were tossed around the most, often violently. It was also the noisiest part of the boat at all times (other than the engine room). As you worked your way up in seniority, you were allowed to move aft to more comfortable and quieter quarters.

Of course the book, "Two Years Before the Mast" aptly describes traditional living conditions in the fo'c'sle. It is a must read for all west coast trawler owners. I suspect most members here already have it in their library.

Sorry for the thread drift.

sunchaser 02-24-2014 12:08 PM

Quote:

Originally Posted by bligh (Post 215594)
I find it amusing that yacht builders have people convinced that 'master' cabins in the fo'c'sle are a good thing.

Precisely the reason mid or aft cabin masters are so popular. A friend sold his KK 48 for forward noise reasons, going to a mid cabin KK in the process. The Fleming 55 is similar in front end master noise level, but when you pay the Fleming bucks you overlook this minor irritation.

magicbus 02-24-2014 01:17 PM

Mid/aft cabins are fine for people who don't like hanging on the hook and sleeping with the windows (and hatch) open catching a breeze. We have no chines to catch the slap anyway so for us it's a moot point. I guess we travel differently than most, but when we're underway I generally don't find time to be sleeping in the master berth, so the fact that the bow does move up and down more than the aft areas is also unimportant. I thinks it's kind of why there are different layouts, not so manufacturers want to "convince you" one way or the other, but because different people actually like different layouts.

Dave

Nomad Willy 02-24-2014 01:20 PM

Shrew wrote;

"The reverse chine on a planing hull is not to reduce spray. It is there to dig in and allow the boat to hold a line in a turn. Otherwise, the hull could start to slip in the turn. This is not necessary in semi-displacement hulls."

Are you sure about that?

I've always thought that type of chine was for
1. Lift
2. Spray control

Never heard of them halving to do duty as a keel as well. For lateral control I would think a keel of the same size as the Chines you speak of would be more effective. Could make turbulence for an OB or IO though.

The chine that you speak of would definitely reduce the amount of banking and produce a more level turn. I have such a chine on one of my outboards but it has so much deadrise directional stability is not an issue. Since this boat (Winner) banks a lot it may have those chines to keep it from halving even more banking.

My Willard has no chine, no spray rails and no need for either.

Shrew 02-24-2014 01:41 PM

The reverse chines would have very little use for spray control. Look at where they are located. They are mid-ship to aft. There is little need for spray control in the strern of a planing boat. The chine doesn't effect the attitude of the boat when turning.

Yes, the chines play a part in adding lift as well.

Ski in NC 02-24-2014 01:49 PM

Quote:

Originally Posted by Shrew (Post 215617)
The reverse chines would have very little use for spray control. Look at where they are located. They are mid-ship to aft. There is little need for spray control in the strern of a planing boat. The chine doesn't effect the attitude of the boat when turning.

Yes, the chines play a part in adding lift as well.

We must be talking about something else- Spray rails and reverse chines that cause noise are in the fwd third of the boat. They do control spray up there, and when anchored do make noise.

Xsbank 02-24-2014 01:54 PM

I have seen some boats where the owners have pulled a thing that looks like a pool noodle under the bow to stop chine slap. Don't know how it was made.

Conrad 02-24-2014 01:59 PM

Quote:

Originally Posted by bligh (Post 215581)
The nordic tug 42 we chartered last year had slap from the chines. My father in law described the sound in the fo'csle as deafening while sleeping up there. Definitely more of a design flaw than a 'compromise'.

The previous owner of our NT 42 added teak ceiling to the hull sides in the forward stateroom, which may have made a difference as the notorious NT chine slap seems to be almost nonexistent. But then my kids say I'm deaf, which could also have a bearing.


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