Hull slapping on chine

Hi all...

I am hoping to join the world boating (again) soon ....I’m sure there are a few Beneteau owners (41s or 44s) that might be able to address my concerns regarding “hull slapping on the chine” and any good or bad experiences with this phenomenon on the Swift Trawlers...

Thanks for any responses in advance..

Jim Nelsen
Jim.nelsen@yahoo.com

You might ask Mainship owners also.

jimbobio said:

Hi all...

I am hoping to join the world boating (again) soon ....I’m sure there are a few Beneteau owners (41s or 44s) that might be able to address my concerns regarding “hull slapping on the chine” and any good or bad experiences with this phenomenon on the Swift Trawlers...

Thanks for any responses in advance..

Jim Nelsen
Jim.nelsen@yahoo.com

Click to expand...

Welcome aboard. That is one of the reasons we have a master aft cabin...

Almost any hull that can plane will have chine slap. My boat does it quite badly, enough that I can hear it in the aft master. But it's not loud back there, and it's pretty easy to get used to. It's one of those sounds that very quickly becomes a "normal boat sound"

I know a guy who bought a second hand Beneteau Swift Trawler 52, used it one day and then got back to his broker with the request to sell it, because he couldnot sleep for all the noises that the water made. Since then he sleeps in hotels in the marina's he visits.



For me the noises are a part of being on the water, it "rocks"me into sleep.

Have a buddy down the dock that had hard slap near the bow.
Won't work for everyone but he solved his issue with strategically placed pool noodles.

You might find this thread interesting:
https://www.trawlerforum.com/forums/s3/bow-noise-51673.html?highlight=Chine+slap+beneteau

What's the scoop on SlapSilencer?

Doing something about chine slapping needs to be done before purchase in selecting a boat. Probably almost any buyers broker would advise a client about chine slappers.

Once you’ve got one get used to it. Or sell.

I travelled on the Great Loop with a guy who had a Mainship. The slap drove him crazy. He sold the boat as soon as he completed the Loop. Nomad is correct. Either get used to it, wear ear plugs, or sell the boat.

Nomad Willy said:

Doing something about chine slapping needs to be done before purchase in selecting a boat. Probably almost any buyers broker would advise a client about chine slappers.

Once you’ve got one get used to it. Or sell.

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This is probably obvious (to everyone else), but I want to check something. Pretty much any boat on my possible list does not have an aft cabin (I like cockpits), so I'll be sleeping in the bow.

I get that a hull like (just to pick one example) a Nordic Tug 32, that has the forward chines (if that's the proper word, but what I mean is they are built into the hull vs. added on pieces) is going to get hull slap.

Is the corollary to that that a boat with a smooth transition at the bow will not (or at least not any more than just the normal sound of waves on the bow)?

I listened to a recording of "before" and "after" from an owner who filled in the forward chines/strakes on his Nordic Tug, and the "before" was really obnoxious (to my ears). Much more than just hearing waves lapping at the hull.

So long question short: If I seek out a boat with a "smooth" bow around the waterline, will I avoid the truly bad slap?

Some Nordic Tugs owners have filled in (with glass and foam) the chine above and just below the waterline at the bow.

https://www.sentoa.org/maintenance_tips/filled_chine_nt_32.html

I just got used to it.

Understood, and it's possible I would get used to it too. Or decide that a given boat had enough other good attributes to ignore it (such as your sweet N26)

But a few people above expressed that one way to deal with it was to buy a boat that didn't do it in the first place, and I'm just trying to ascertain the cause. I see that a Nordic Tug (not to pick on them; the reason I now this is that I do like them!) has a "formed in" strake or chine (not sure which you'd call it) such that there is a little "ledge" in the hull right at the waterline in the bow. I believe this is what causes the slap.

So.... does that mean that on a bow that is smooth (without that chine) at the bow waterline will not make the slap? Or just how does one avoid it in the boat selection process as Willy suggests above?

You guy just aren’t tired enough. A couple shots of rum and the slapping goes away.

Or bourbon. Seriously though, I'm surprised wave slap comes up so often. Sleeping on the boat is an orchestra of noises - creaking mooring lines, the A/C running at the slip (including the sound of running water all night), the refrigerator kicking in, nearby sailboats with rigging clanging against aluminum masts in the wind at night, or wind whistling in the rigging, the dingy bumping against the swim step -- or when we boated New England, buoy bells clanging, seagulls screeching. Heck, wave slap is a lullaby.

Our aft cabin must be very well insulated or something. We were tied up on the Hudson about a hundred yards from the commuter train station that runs to NY. We were worried that the trains would keep us up all night. We really didn’t notice the trains at all during the night. Much less wave slap.

Hard to describe, but if you can see a recess or pocket where the chines start, at water level,you can see where waves would strike and resonate. I believe Mainships were identified as "slappers", maybe look at one and see if what I remember is borne out. As to the ST42, I was interested in one but passed for other reasons, it may have been identified as a "slap" candidate, I can`t recall for sure.

Earplugs.

Frosty and OP,
Nordic Tugs, due to their bow structure can experience wave (bow) slap. We have had a couple of nights where it was terrible, but mostly you can get used to it.
Several NT owners have spent (a fair bit of) money getting some permanent, fibreglass work done to the bow area and have reported great success in reducing or even eliminating most of the noise. It is my understanding that the NT bow design is supposed to reduce waves (green water) over the bow and making a "dryer" boat. I don't know this as fact however, and I have not heard of any owners who have "adjusted" their bows for wave slap, complaining that they noticed more water over the bow or any noticeable drop in performance.
For us light sleepers, ear plugs do help.

Amongst other boats in our family... We had a "Johnson Bros" lapstrake wood boat. That lasted for only one season in NY. Dad went crazy hearing the slap on the strakes; he and mom slept in the forward berth.

Different than chine slap... in that: Chine slap is one to three or maybe four rather loud knocks per wave contact. And, lapstrake is a bunch of lesser noisy, but many more multiple knocks as well as sort of a suction sound as the wave travels up and down the non chine lap strake hull sides.

Thanks to master cabins in rear the chine slap is no problem.

firehoser75 said:

It is my understanding that the NT bow design is supposed to reduce waves (green water) over the bow and making a "dryer" boat. I don't know this as fact however, and I have not heard of any owners who have "adjusted" their bows for wave slap, complaining that they noticed more water over the bow or any noticeable drop in performance.

Click to expand...

The article I read was a link from one of the NT owners' sites. It was a pdf showing how the owner had that forward chine permanently filled in for a certain length forward and aft of the bow waterline at rest*.

He had recordings you could play of the before and after. The after, to me, sounded like normal, after-all-you-are-on-a-boat water/hull noises. In other words, not gone, but not unexpected. The "before" was (IMO) more annoying, with hollow "schlonks," suction noises, and loud bangs in random but kind of "listen for the next one" patterns.

He mentioned (or maybe it was someone else who had done the same job) that when motoring faster than hull speed, there was enough bow rise that the filled in section was out of the water anyway, so the chine/no chine would at least not have been doing anything at those speeds.

Apparently NT does fill in some of the larger ones now right as they built the boat (40xx footers).

I would love to own a 37 NT. Swoon! Wouldn't kick a 32' out of the slip either

So what I'm taking from this thread is that if you want to avoid it during the boat selection process, look for one without that little chine at the forward waterline. (Or plan to get used to it, or fill it in.)

Frosty

BTW, I'm not against any water sound at anchor. Years ago I had a lapstrake style hull. Talk about hearing water sounds at anchor! But it was more regular "light but constant" sound if I had to describe it.

*I went and looked and here is a link to the article, including photos, if anyone is interested:

https://www.sentoa.org/maintenance_tips/filled_chine_nt_32.html

I couldn't figure out how to extract them, but there are links to the "before" and "after" sound within the article in case anyone wants to have a listen.

I can add that if you’re anchored, turning the boat stern-to may eliminate the slapping. And w a bridal attached to the stern cleats .. one on each side .. may eliminate “sailing” also.

Nomad Willy said:

I can add that if you’re anchored, turning the boat stern-to may eliminate the slapping. And w a bridal attached to the stern cleats .. one on each side .. may eliminate “sailing” also.

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Stern to gets rid of the chine slap, but on many boats, the slap and splash against the transom and swim platform is as bad or worse.

Nomad Willy said:

I can add that if you’re anchored, turning the boat stern-to may eliminate the slapping. And w a bridal attached to the stern cleats .. one on each side .. may eliminate “sailing” also.

Click to expand...

Due to anchoring conditions throughout islands in SF Delta we are often front and rear anchored; nosed toward/into island edge - rear toward the slough/channel. This leaves our transom exposed/susceptible to wakes from passing boats. Due to speed limits and most captains' good seamanship there are usually no boats creating large wakes in the sloughs... so our boat gets not often rocked by wakes. That wakes hit us square on the stern means the "rocking" is in length of boat not width. Lengthwise rocking from wakes is way less bothersome than from on the side... virtually unnoticeable in comparison.

With that said: When anchoring such as this... wakes can force water into exhaust pipes on the transom; possibly way up into the engine [depending on exhaust configuration]. I strongly recommend to have Exhaust Flappers attached to the exhaust pipes.

https://www.westmarine.com/buy/sier...MI4_341u2Z7AIV1cDICh1pVwRWEAQYASABEgItUfD_BwE

Our NT 37 has the chines and the infamous chine slap. Its usually not bad at all. I keep earplugs aboard as I thought I needed them once. But I have yet to use them . The noise I dont notice anymore and it blends into the other cacophony of noises that you experience when sleeping aboard.

Aft cabins are usually closer to the ERs, so sleeping aft is not always that advantageous. I remember once in my youth a captain woke me in the wee hours up to help reset the anchor as he could heard the anchor dragging from his bunk. His cabin was not the focsle, but he was well forward of the engine room and could hear it.

Even though I am getting ready to sail my NT37, the chine issue would not affect my decision to buy another NT. I can live with the chine slap. If you are a sensitive sleeper you will have to deal with other noises as well.

firehoser75 said:

Frosty and OP,
Nordic Tugs, due to their bow structure can experience wave (bow) slap. We have had a couple of nights where it was terrible, but mostly you can get used to it.
Several NT owners have spent (a fair bit of) money getting some permanent, fibreglass work done to the bow area and have reported great success in reducing or even eliminating most of the noise. It is my understanding that the NT bow design is supposed to reduce waves (green water) over the bow and making a "dryer" boat. I don't know this as fact however, and I have not heard of any owners who have "adjusted" their bows for wave slap, complaining that they noticed more water over the bow or any noticeable drop in performance.
For us light sleepers, ear plugs do help.

Click to expand...

Nordic Tugs are wet boats on a head sea.

I don't think the reverse chine does much for rolling the bow wave outward on a slow plumb bow.

It transitions well to the hard chine, though.

It also makes the boot stripe a bugger to paint.

Northern Spy said:

It also makes the boot stripe a bugger to paint.

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I'll agree with this. Taping out my boot stripe where it crosses the bit of reverse chine up forward is a pain, as it ends up making somewhat of a Z shape, but on a multi-faceted surface.

Art wrote;
“this... wakes can force water into exhaust pipes on the transom; possibly way up into the engine [depending on exhaust configuration]. I strongly recommend to have Exhaust Flappers attached to the exhaust pipes.“

Glad you mentioned that Art. Probably over time it could fill up a lift muffler.


Northern Spy wrote;
“I don't think the reverse chine does much for rolling the bow wave outward on a slow plumb bow”

I always thought NA’s just thought they looked cool. Still do.

Arc said:

You guy just aren’t tired enough. A couple shots of rum and the slapping goes away.

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Chine slap, oh yea
TOO quiet at home.

If you want distraction, turn the radio or tv on.

You hear the lady screaming on the next boat over, one does not know if one should call the police or congratulate him in the morning.