“Keel walking” on series 1 convertibles

[The Hatt]

“Keel walking” on series 1 convertibles

Perhaps you guys are the other 207 people that watched this video on YouTube, but in case you weren’t, I thought I’d post it here:https://youtu.be/dirBIsgblt4It’s a presentation from Bruce Angel, EVP, chief technology officer at Hatteras.He had a couple interesting slides on the “keel walking” phenomenon seen when repowering series 1 convertibles, and offers a simple fix that doesn’t require adjusting the keel.I thought this might generate some good discussion here. Let’s put some 6bts and qsm11s in more of those 36-42 series 1s and keep those boats relevant!

 

[madhatter1]

Re: “Keel walking” on series 1 convertibles

Link not working. My 34 with 6BT's 270HP can hit 31 MPH with no keel walking. Friend had a 36 with 350 Yenmars and at one point with the fuel pumps turned up too much I think he hit 38MPH with no keel walk. Is it just the bigger boats? My 82 46 HP has a modified (at factory) keel but I don't even know what the differences are.

 

[The Hatt]

Re: “Keel walking” on series 1 convertibles

https://m.youtube.com/watch?v=dirBIsgblt4Try that link.

 

[brian4190]

Re: “Keel walking” on series 1 convertibles

My 1985 36’ series 2 convertible will start falling over at about 26 knots . This is not a problem as my cruise is around 20-22 The big issue Is running In large following seas when going at anything faster than displacement speed the boat will fall on its side when it starts surfing down the wave. It is very disconcerting especially to people on board that have not experienced it before. It’s too bad as the boat is extremely seaworthy otherwise. a temporary fix is to according to the Bruce angel is to tie a line to the two mid- forward cleats passing under the boat tight against the keel. When I talked to him he suggested trying this first before doing the permanent fix of attaching a one inch square batton to the hull still have not had the opportunity to try it yet to see if it works.

 

[krush]

Re: “Keel walking” on series 1 convertibles

This is an awesome presentation. The engineer talk is legit and right on....that guy has many lifetimes of knowledge. I hope the PE (private equity) guys allow it to be passed on.

 

[The Hatt]

Re: “Keel walking” on series 1 convertibles

Agreed. The “keel walking” commentary is just one portion of it.Curious if anyone with one of these older boats has tried either of the two suggestions mentioned.... line under the hull or the 1 in. battens.

 

[SKYCHENEY]

Re: “Keel walking” on series 1 convertibles

I be interested to see the orientation of the battens. Has anyone done this?

 

[brian4190]

Re: “Keel walking” on series 1 convertibles

When I talked to Bruce he recommended the line to the cleats first to see if that worked if so you would know where to place the battens you might need to experiment around to find the right spot. he alsosaid the battens would be completely below the waterline. I honestly don’t know if it has been done before on anyone’s boat or if this I just a theory of his

 

[Cricket]

Re: “Keel walking” on series 1 convertibles

I've been wanting to add strakes for quite sometime, just haven't been able to figure out where to place them. Would like to get the stern up some and also hold the bow up when riding a down sea wave, the oversized rudders along with power steering have been a huge help with control in a following sea. There's lots of these old Hatt's with all types of below the water line additions, many years ago watched a 52c having trying on different placement and sized strakes at American in Stuart, they were hauling the boat a couple times a day moving stuff around, never found out what the end result was.

 

[Wiredup62]

Re: “Keel walking” on series 1 convertibles

I had a 1975 36 convertible that had been repowered with 440 yanmars. The repower was prior to me owning the boat. When they did the repower they added a 4-5 inch spray rail all the way around the boat to add bouyancy and keep the boat from wandering. It cruised at 27-28 knots, and did still keel walk a little, but I think would have been much worse without the rail. More interesting was when turning the boat, the rail was so big that the boat turned flat, meaning you never leaned over into the turn.

 

[MagnaBill]

Re: “Keel walking” on series 1 convertibles

Thank you - great link to the presentation. Really great info. Interesting he seemed to say interceptors now the way to go over trim tabs - that's what he said right?

 

[Wiredup62]

Re: “Keel walking” on series 1 convertibles

Thank you - great link to the presentation. Really great info. Interesting he seemed to say interceptors now the way to go over trim tabs - that's what he said right?

I just added the humphree interceptors to my boat, as the small tabs Hatteras put on basically did nothing, and WOW, what a difference. They are phenomenal, way better than normal bennett tabs. They are very quick to control, automatically retract when in neutral, and just a pleasure to use and see the differences they make.

 

[Cricket]

Re: “Keel walking” on series 1 convertibles

Can you tell us the difference between the Humphree product and Zipwake, etc.
Also, what are the actual performance improvements you're seeing compared to the "regular" type trim tabs.
I've heard people say they take some of the roll out while underway, anything to that?
What modifications to the transom had to be made to install them?
Very curious, thanks.

 

[Wiredup62]

Re: “Keel walking” on series 1 convertibles

Can you tell us the difference between the Humphree product and Zipwake, etc.
Also, what are the actual performance improvements you're seeing compared to the "regular" type trim tabs.
I've heard people say they take some of the roll out while underway, anything to that?
What modifications to the transom had to be made to install them?
Very curious, thanks.

So, called zipwake first and they said their product isn't big enough for a 60 footer. They are working on one but not ready yet. Humphree interceptors are basically the same thing as zipwake, just a little more commercial and for larger vessels. &nbsp.

My 2008 60c gt only had a small hydraulic ram inside each prop tunnel, which provided almost no help in lowering the bow when running. The interceptor control at the helm gives you your running angle, and with no tab I was running about 6.5deg. When I hit the button at the control panel the vertical blades drop almost instantaneously, and with them down you can instantly see the bow drop and run at 5.1 deg. I haven't tried all the way down, worried about digging the bow in, lol. There is a ton of programming you can do so the tabs will automatically adjust based on your speed. The interceptors have different modules you can get, anti roll is one of them. With that, the tabs self adjust to keep you running vertical almost like having a sea keeper at speed.

 

[Cricket]

Re: “Keel walking” on series 1 convertibles

Thanks for the info. Hopefully they will help lower the amount of roll on the troll too.

 

[madhatter1]

Re: “Keel walking” on series 1 convertibles

Thanks for the info. Hopefully they will help lower the amount of roll on the troll too.

They won't do anything at troll. You need speed to create the pressure that makes them work. And at speed they do work amazingly well. Had an earlier version (Volvo Q-something) on my 34. But growth locked then up and the ones I had broke because the gears inside were plastic. If newer versions are sturdier they are definitely work looking at. But x amount of years ago I just went back to Bennet's and put on the dual rams for durability. They have worked very well.

 

[Wiredup62]

Re: “Keel walking” on series 1 convertibles

They won't do anything at troll. You need speed to create the pressure that makes them work. And at speed they do work amazingly well. Had an earlier version (Volvo Q-something) on my 34. But growth locked then up and the ones I had broke because the gears inside were plastic. If newer versions are sturdier they are definitely work looking at. But x amount of years ago I just went back to Bennet's and put on the dual rams for durability. They have worked very well.

These new ones are very sturdy!! They also have a feature to automatically deploy every few hours while at the dock so they don't get stuck or fouled up. The only negative so far is that they do stick out from the transom about 6", which could be an issue fishing. In the first photo you can see the tiny tab that hatteras put on in the center of the prop tunnel.

 

[harnett]

Re: “Keel walking” on series 1 convertibles

Which model and size did you end up going with?

 

[jim rosenthal]

Re: “Keel walking” on series 1 convertibles

Great link. Are there typical speeds that the older hulls keel-walk? (or whatever it's now called) I have run my Series 1 36C over 31 knots and not had that happen.

 

[spartonboat1]

Re: “Keel walking” on series 1 convertibles

https://m.youtube.com/watch?v=dirBIsgblt4Try that link.

Fascinating!!! Thanks for the link...