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?

Bohans said:

Any thought?

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Ear plugs

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.

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.

Ski in NC said:

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.

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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.

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.

Scottsdale AR

Ahab7 said:

Scottsdale AR

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Morris Plains ND

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

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

the sound of snow melting - YouTube

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'.

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.

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.

bligh said:

I find it amusing that yacht builders have people convinced that 'master' cabins in the fo'c'sle are a good thing.

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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.

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

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.

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.

Shrew said:

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.

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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.

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.

bligh said:

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'.

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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.

I like my hull, no noise at anchor. I have in the past owned fast noisy hulls and tried to convince myself that it was a soothing sound, but it's not, it's noise.

I have changed from an all chain rode to 60 ft of chain and the rest nylon square line and am astonished at the quiet at anchor.

I like quiet.

Here's some pics of my uncles boat he added the chines for spray amidships/aft and lift if memory serves right. Hope this helps.

There are a few different "slapper stoppers" out there. Funny you should mention a Nordic Tug 42 as the only guy I know with a slapper stopper has this boat.

Hey... for real fun - try sleeping in V-berth on a 32' lapstrake woody. My dad bought one, a Johnson Brothers boat in late 50's... lasted less than one NY boat season till he sold it. Constantly sounded like loud perking coffee in an old glass top / stove top coffee percolator, even in dead calm water. If someone so much as rolled over in bunk or walked to use the head in calm water the noise would co on for minutes When a wake hit or wind created even tiny waves you might as well get up and play cards - no sleeping possible! I detest lapstrake boats for that reason, alone!

BTW - Our Tolly makes not a sound to interrupt sleep

hull slapping

This subject comes up a couple of times a year in this and other tug/trawler forums. Since I have the "notorious' Nordic Tug, I'll add my 2 cents.

Nordic Tugs, a semi displacement hull with hard chines, does have a notorious rep for hull slap. The first night on the mooring, I knew I had to do something. Canvas wave slap preventers, which I made up, do work (picture attached), but a pain to deploy, and a safety factor when anchored out (not to mention embarrassing). Putting 4" of sound deadening foam panels inside the hull muffled the slap, but did not eliminate it. I took the plunge and filled in the chines... a combination of bonding in CoreCell foam panels, covered with a couple of layers of carbon cloth and layers of epoxy resin. Problem solved, with no impact on performance, lift, or wave deflection. I know several other NT owners that have filled in chines. The chine area filled in on my 18 knot top-end hull is several inches aft of where the water meets the chine and going forward for about 48". As the hull lifts up above 7-8 knots, the filled area is out of the water.

We just get up and slap the water right back, it soon gives up and we sleep well.

Anchored the windage is about the same if you anchor by the stern.

Even by the stern quarter might be less noisy , but at 3 AM some doofus might want to >rescue< the boat.