Dealing with "chine slap"

[Cap’nJack]

I'm a trawler newbie, but experienced offshore sailor with over 1,000 nights at anchor. When I bought my first trawler, a North Pacific 36, I experienced the new-to-me Chinese water torture of water slapping against the hull while sleeping in the V-berth. I tried putting a bunch of bedding under the V-berth, I made a "necklace" of pool noodles to be a mini breakwater, and finally talked to the owner of North Pacific Yachts. He said one person tried a new sound-deadening paint (ineffective), and another had a yard fiberglass over the chine where it cuts the water, potentially eliminating the sound (results unknown). Our anchorages here in the Puget Sound are very protected, but you wouldn't know it from the sound in even a soft breeze and minor fetch.

Was this unique to our boat, or do other boats have the same problem with the water slapping against the chines while at anchor? We are looking to buy something in the 38-42' range, and limiting our search to hulls without chines cuts into an already small list of potential boats.

 

[Portage_Bay]

Look at boats with the master cabin in the "back end". Or full displacement round bilge boats. I've had Tollycraft, Californian and West Bay all with chine slap. I've had an old wood full displacement and cruised a KK 42. No chine slap.

 

[BruceK]

You learned the hard way to recognize "a slapper". There are boats which do, and don`t. It`s evident in the chine design, I had one which did, albeit moderately, and 2(an Island Gypsy and an Integrity) that don`t at all. I`m sure you`ll avoid it in your next boat.

 

[dhays]

I have a NP 43 and most of the time don't experience the slap, but can occasionally. It doesn't usually bother me much, but when it does I find earplugs take care of it.

I experienced a LOT more slap with my Catalina 400. It has the master cabin in the stern and it was very significant.

FWIW, I get a lot more noise from the burgee flag pole rattling in its mount. The sound is transmitted from the rail throughout the boat. There have been a number of nights if the breeze has come up where I'm out on deck in my skivvies removing the burgee staff.

 

[O C Diver]

My boat had chine slap. I was abe to eliminate most of it by filling in the chine where the bottom paint starts. When anchoring in >1' seas, the waves hit where the chine wasn't filled in.

The other option is to stern anchor when conditions permit.

Ted

 

[Hippocampus]

Ted has it right. See it with chines, lapstrake and even some low rub rails. NTs are notorious for it in certain conditions. Some make a mixture of mirco balloons and thicken epoxy and fill in the offending area. Usually just at the waterline and a few inches to a foot up and maybe a foot or less back along the chine. Doesn’t take much as only a small area is responsible for the slap.
I haven’t done that on my NT. Kind of like the slap. It isn’t loud and find it restful and rhythmic so soporific. Wife doesn’t mind it either.

 

[jgwinks]

The chines on my 41 MY probably slap, but with the master berth in the stern I can't hear it. There are other things that have gotten me up in the middle of the night though.

 

[SoWhat]

Soft foam ear plugs.

 

[Shrew]

birds, shrimp, halyards slapping, chine slap, waves, wind in the antennae. It's just part of the experience. Most people from large cities find the country disturbingly quiet. People from the country find the cities noisy at night.

We bought a house about 1/4 mile from a train crossing and the trains cross and blow their horns roughly every 90 minutes all night long. Once every week to 10 days Elon Musk launches a rocket a few miles away in the middle of the night that shakes my house. Believe it or not, we very quickly learned to sleep through it.

The sounds of the water, including chine slap will go away with enough repeated exposure.

TLDR: You'll get used to it.

 

[DDW]

Nordic Tugs and American Tugs (similar hulls) all seem to do this. Several owners have filled the strake as suggested above, and report that it solves the problem. It is easy enough to fill the strake, but the finish work required to make it look good is expensive.

 

[Marco Flamingo]

The sounds of the water, including chine slap will go away with enough repeated exposure.

Even better, once you get used to it, it will put you right to sleep. I should make a recording and bring it home.

 

[guy with a boat]

Lots of boats make some noise from some version of chine slap, but it can range from insignificant to unbearable. OP, you are right to do your homework on a boat model that you may be considering. Don’t rule out everything with chines at the bow, but research other owner’s experiences for the particular boat model.
I’ve been on boats where the noise was noticeable but not problematic. I’ve also been on one boat that was so loud that it was impossible to sleep in the bow with wind chop on the water.

 

[BruceK]

Lots of boats make some noise from some version of chine slap, but it can range from insignificant to unbearable.... Don’t rule out everything with chines at the bow, but research other owner’s experiences for the particular boat model.
I’ve been on boats where the noise was noticeable but not problematic. I’ve also been on one boat that was so loud that it was impossible to sleep in the bow with wind chop on the water.

True. Experiences will vary, to some the slap becomes music, to others intolerable, leading to abandoning the fwd cabin. It`s a potentially miserable ownership to assume you`ll get used to it, you may very well not, choose carefully.

 

[Sababa]

Nordic Tugs and American Tugs (similar hulls) all seem to do this. Several owners have filled the strake as suggested above, and report that it solves the problem. It is easy enough to fill the strake, but the finish work required to make it look good is expensive.

This indeed solved the bow slap problem on our former Nordic Tug 37, but it set us back nearly $20k. Money well spent because my wife could not otherwise sleep on the boat.

 

[DDW]

I think there is a much cheaper way to accomplish filling in the chine, I may pursue that one day. There are enough Nordic Tugs and American Tugs around, it could be offered as a product. I note that on the new Nordic Tug 40, they modified the hull mold to eliminate the chine.

 

[rslifkin]

On some SD boats the chine isn't particularly necessary for performance and can safely be filled in. But on some faster SD boats and particularly planing hulls, the chine is important and filling it in is likely to hurt performance at higher speeds.

My boat has down-turned chines up forward, so there's some slap when anchored with anything more than slight ripples hitting the bow. It has to be pretty sporty for it to get annoyingly loud (especially in the aft cabin), but I've never found it to be a particularly annoying sound. On this boat it's just a rhythmic watery thumping, kinda like a "bloomp" sound. It's not a harsh slapping noise, so it pretty quickly becomes a normal boat sound.

 

[Sababa]

The standard modification for the Nordic Tugs softens the chines forward to just below the waterline and blends into the hard chine aft to maintain semi planing performance. The final shape is a lot like what you see on a Fleming.

 

[jleonard]

I used to get chine slap when i had my old Mainship. I actually liked it, it put me to sleep. On a calm night if it woke me up i knew that the wind picked up or my direction changed so i would go out and check the situation.
It does have advantages.

 

[DDW]

The chine in question is more properly called a spray rail, and is just an out turned step a couple of inches wide. Its purpose isn't to promote planing (far too small to make a difference there) but rather to turn the spray from chop or planing outboard. The only part that causes the slap problem is about 6" below to 6" above the waterline. Because of the flat angle, that ends up being 3 or 4' of chine. It is really hard to see how filling it would impact performance, might make it a little wetter in certain conditions but a number of NT and AT owners have filled it an none I know of have reported any operational difference. Only a reduction or elimination of the slap.

 

[Cap’nJack]

Thanks all for your comments. With probably 300 nights at anchor in our North Pacific 36, even wearing ear plugs and filling the area below the V-berth with dozens of pillows didn't help. It looks like I will need to pursue boats that don't have a chine or spray rail.

 

[Cap’nJack]

I have a NP 43 and most of the time don't experience the slap, but can occasionally. It doesn't usually bother me much, but when it does I find earplugs take care of it.

I experienced a LOT more slap with my Catalina 400. It has the master cabin in the stern and it was very significant.

FWIW, I get a lot more noise from the burgee flag pole rattling in its mount. The sound is transmitted from the rail throughout the boat. There have been a number of nights if the breeze has come up where I'm out on deck in my skivvies removing the burgee staff.

I really liked my NP-36 except for the sleepless nights. One of the boats I'm considering is a NP-43 like yours, but I'm wary of having the same problem. Trevor at NP said some had fixed the problem by filling in the gap as others describe, and his newer designs (out of my price range) have a smooth hull. My Pacific Seacraft 40 is for sale...perhaps you'd like to buy it - it is very quiet at anchor!