following sea

B

B~C

New member
How do you handle a following sea?
myself, on big rollers, go like hell with the trim tabs in the go fast mode and a big grin.
On the big steep stuff, with the trim tabs up, I go slow and pretend I'm a bird, just let them pick me up and then go like hell on the backside untill I'm almost back in the trough then throttle back to just off idle and start all over again. I'm always using that throttle and looking behind me, usually leave grip marks on the throttles.
On big breaking waves, same as above but with the seat clinched real firm with the pucker muscle, all the while wondering what the hell I'm doing out there cuz I shouldn't be.

you?
 
BCK, Your scarin me! Always wondered how to take on this kind of stuff since I haven't been exposed to it. This explains the indentation on your helm seat.
 
Good one :idea: 8) and I got no "one way" of doing it. There are times I have only enough throttle to keep baby pointed in right direction, and enjoy the sees running under me, and there are times play surfer-dude, and run back and forth on them, trying to ride each swell out as much as possible :o ... seems they always have a way of disappearing on you (as in; where do they go?) Tricky :!:

Mostly though... trim tabs are always up as far as possible, cuz I need to keep engine trimmed-down far as possible (cavitation) :disgust I can't wait to get a better hydrofoil... maybe I'll have better control, if I don't have to trim-down so much in a following-sea :|
 
Redƒox":28x7cb47 said:
Good one :idea: 8) and I got no "one way" of doing it. There are times I have only enough throttle to keep baby pointed in right direction, and enjoy the sees running under me, and there are times play surfer-dude, and run back and forth on them, trying to ride each swell out as much as possible :o ... seems they always have a way of disappearing on you (as in; where do they go?) Tricky :!:

Mostly though... trim tabs are always up as far as possible, cuz I need to keep engine trimmed-down far as possible (cavitation) :disgust I can't wait to get a better hydrofoil... maybe I'll have better control, if I don't have to trim-down so much in a following-sea :|
Click to expand...

My old motor used to cavitate but the new 4 stroke Suzy with the 20 pitch prop just grabs, love it.

As far as one way to do it, good luck. I play her bt feel each time. The only thing for sure is that it will be different next time and it will change about the time you think you have a feel for it.

Me, I count the swells and go with it. I like to find that "ninth swell" to get a good long ride. It conserves fuel and it is fun. I enjoy throtteling back and flying back to port.

I don't have my tabs installed yet but the plan and practice will be to have them full up when heading in.
 
Yes :!: :idea: :thup Best reasons for the big Yami's and Suzy's is the fact they turn a steeper-pitch prop, and deliver a better ride thata way to.
I keep gettin heavier and heavier :embarrased So I stepped-down to a 17-pitch. I noticed a gigantic difference from a 17-pitch to a 15-pitch on my older two-strokes. I could not swing a 19 on them :thdown and when I had to put on the 15-pitch the ride really started sucking in the swells... front-end would fall off the wave-tops with a vengeance :amgry the 17 was a dramatic improvement! 19 and 20 even better, but not by much! 17-pitch was the barrier.
Maybe I'll put my 19 back on, but I really like the way the 17 rockets the RedFox out of the hole when she's really heavy! Better for the engine to not lug her so much :idea:
Your Suzy is geared-down a notch lower, but has to have reduction-gears to achieve it. I'm pretty sure my Yami' is direct-drive to the lower-case. You runnin' a hydrofoil... :?:
 
Greg,

Are you using a prop with a lot of rake (blades lean aft)? A high rake prop tends to lift the bow. That would keep the bow up when starting over the crest of a wave. Evinrude sells a stainless steel prop called The Raker for bow heavy boats.
 
No foil here Greg ol' buddy.
I am hoping to get the trim tabs on within the next few weeks. I have been putting it off because I can not afford a kicker bracket.
 
ARG... I'm thinkin I got screwed on that "hydrofoil" I now have. Sure looks purdy, but I think I cavitate worse with than without it :disgust Off with it's head! :thdown :amgry

Larry you won't convince me there is a "free lunch" prop out there for them high-geared outboards :wink :wink:

OK... I better get off B~C's thread now... :embarrased
 
aint my thread, Iza just thowing up a thought for discussion. I wonder how the TC would handle the large steep stuff
 
Seas today were real lumpy, maybe 3-4 feet and close together, whitcaps starting. No problem heading into them (9-10kts), but running back with them on my port quarter, and at about 15-17kts, I was getting some cavitation (ventilation?) of the port engine, rpms racing ahead. Was running with tabs fully retracted, and trim about neutral. Got it to stop by slowing to about 12kts. I see from this thread others have experienced this same thing? Is there something I can do with the tabs to counter it? I did tuck the engines under a little with the trim control, which helped a little, but not enough to get back up to speed.

Interesting comment, Greg, about your hydofoil. I haven't yet added DoelFins to my new engines. By your comment, I'm not sure I should add them.
 
....oops :o almost missed your question Joe :|

It's true-blue for the RedFox alright; the last hydrofoil was a sham. Its only the second one (brand) I've tried, and having given them things a fair chance at proving themselves sea-worthy, has failed to impress. One brand did stop some venting, the other I'm pretty sure made it worse! It was a cool looking unit, and on sale at one of our local marine stores---and I fell-for-it again... :oops: now its off to stay! From what your describing, I'd say adding one would only make it more pronounced :!: :x

What happens down there is; the faster you scoot-down-seas, the more stern-lift. For trailing-sea-enjoyment; you must be "stern-heavy" to keep the end of the boat that controls----in control---the stern. :idea: The more gadgets that lift the stern and burry the bow (as we need to do sometimes) like trim-tabs and hydrofoils, the more ill-handling your going to in for out in them nice big-ass'd-seas :crook :shock: RedFox does great with her huge-trim-tabs cuz she's rigged for them: more-stern-heavy.
Having the tabs and lots of weight back where its needed, I have control in any situation---stern-down, stern-up.

Hope that was clear, I don't do so well at bein clear sometimes :embarrased
 
Right on, Greg. In following seas, it's vital to keep the bow up, stern down. I had my tabs in the full up position, but had two other people aboard in the cabin, which might have given me more weight forward. Hell, I was more worried that with those two 4-strokes back there I'd be too stern heavy. I might try some starboard tab to lift the starboard side and keep the port side down, when in a port quarter sea again.

The DoelFin issue is interesting......they are designed to lift the stern, but it would also seem to help to prevent ventilation. I had them on my old Sealife and they worked well.
 
Now that Greg has drug me into this, I'll have to get my feet wet, so to speak.

It seems that the overtaking motion of a wave from the rear wants to lift the stern of a boat, then if that happens too much and the bow digs in, the net effect is to broach the boat sideways.

Thus we have the admonitions to keep the bow light, the stern heavy, and eliminate any additional leverage points for the wave energy like trim tabs and hydrofoils.

This makes me think that the ideal boat in this situation would be a heavy deep hulled double ender to minimize the effects above not wanted on the rear of the hull. No wonder so many of the very seaworthy trawlers, tug boats, and ocean going sailboats have double ended designs, and also are "positive displacement" boats that certarinly don't plane, but use pure mass to help achieve stability.

Thus Red Fox's admonition to load up the arse of the boat to stabilize it's behavior at displacement speeds is right on with both empirical observation and established naval architectural practice and theory.

This is the most apparent limitation of the light dory approach to design: when the boat meets following seas. The cork, floating on its side, narrowed end forward, gets it's butt pushed around by the energy of the oncoming waves from behind.

Weren't some of the Melben Marine's custom 25-30 foot workboat double enders? (Melben Marine was the original C-Dory builder, I believe. See the company history on the C-Dory Manufacturers website.)

Does the original flat bottomed "Classic" behave differently than the later 2-degree slightly v-bottomed boats in a following or other seas?

How do these considerations relate to the performance of the older and newer Tomcats with their two narrowish hulls?

Better quit for now! Joe.
 
Well, Joe, that's probably why the Toland's used to discourage trim tabs on their boats. C-Dorys have a natural bow down attitude (most evident at rest) which contributes to this problem. It's also a reason it can slow down so much in rough seas and still stay on plane, so it's a trade-off. As C-Dorys have evolved and gotten so much more popular, adding twin engines, and 4-strokes have put additional wieght in the stern, probably helping this problem, but narrowing the amount of freeboard at the motor well. Perhaps one solution is not to run with a quartering sea, but to take it dead astern, tacking somewhat to reach the destination.

I'll say one thing though, my Raymarine ST6001 SmartPilot works like a charm, dead on course, no matter the sea direction. Just up the response level for following seas, and it track perfectly. Great unit.
 
I wish I could say the same about my ST6001 unit. It has not worked the way I would like since day one. On this last trip I removed all metal that I could find from under the stove area where the fluxgate is mounted. I was keeping stainless and aluminum pans there. This did seem to help and it held course for the most part. But even when it is working well it will be off course by .02nm to .03nm. Seems like it should stay right on course when it is flat calm and little current.

Steve
 
Since I replaced my unit - it is now working really well. I've started adjusting the response level for trolling (way down) and high speed cruising (up a little). It works great.

Any chance the settings in calibration are wrong? Les changed mine from when he initially outfitted Two Lucky Fish. I left the manual on board, but would be glad to review the settings if you want. I remember that it wasn't what I had thought it should be.......

mac
 
My Raymarine ST6001 autopilot has been a problem pretty much from the outset and worsened as time went on. It took a spell where the autopilot would constantly hunt the engine back and forth which was irritating to say the least. This past summer the display would show the boat going in the wrong direction and in some cases 180 degrees off. This continued to get worse until I could take a heading toward a point and reverse my course and the autopilot heading remained unchanged.

I sent the unit in to Raymarine and just recently got it back. They upgraded to the newest software and said they located the problem. One of the components was soldered in backwards, which they corrected.
Also, mentioned that they had a number of the units that appeared to be working ok initially but were flawed and they degraded over a relatively short period of time and required service. They said they've corrected this problem.

The good news is that I merely disconnected the power to the autopilot this summer and fall and that corrected the problem of the boat not showing the true course of travel on the display. Thus, I was comfortable with the Ray...C80 system navigating the abundance of fog we had this past season. The bad new is that it's snowing outside right now and I won't be able to recalibrate and confirm the autopilot fix until next spring..........sigh.
 
Sea Wolf":9y2h1jsr said:
It seems that the overtaking motion of a wave from the rear wants to lift the stern of a boat, then if that happens too much and the bow digs in, the net effect is to broach the boat sideways.
Click to expand...

I found myself in this position a few months ago, having come accross a swell near portlock, oahu -- about a seven foot swell came out of nowhere on a fairly calm day. (I found out later that the area is to be avoided unless you're a surfer)

Suddenly broached and seeing the top of the wave in the port window and the bottom of the wave starboard had me sweating bullets.

Overall, I find following seas a bit dodgy and I try and avoid that scenario as much as possible. Otherwise, I just deal with it by tacking or managing speed to minimize the impact.

Otherwise she is a very good boat for these waters. Especially with the cabin for shelter from high winds, random rain and hot sun. She has gone out fishing on many a day when it was too windy or inclimate for other boats her length!

Kris
 
Kris-

Sounds like you've been there, done that!

I noticed you just joined up today. Welcome to the C-Brats!

How long have you had the C-Dory, and how long have you lived in Hawaii? Is your boat trailered or moored? Do you know of any other C-Dorys there?

If you'd like an album in which to put photos of your boat and other activities, Mike (Tyboo) or Bill (Da Nang) can set one up for you.

Nice having you aboard! Joe.
 
Sorry to continue on about raymarine problems on this thread about following seas, but I am interested in those settings that Mac mentioned. I've been experiencing problems since the Blakley gathering when the boat was only two weeks old. The chart appeared 20 to 30 degrees off in head-up mode and radar returns were offset from the chart. On the next daytrip the system appeared to be okay (or close), but on the following trip the problem was event as soon as we departed. The chart was a good 30 degrees off and it hit me --- metal items stored by the fluxgate, hmmm! So, with the autopilot ON I told Lynn to watch the helm and I looked under the cabinet and found a container with canned goods had shifted aft against the bulkhead. The boat made an immediate turn to starboard as I shoved the container forward --- got it! But since then I still am having the same problem despite having moved problem items. And I am also getting XTE errors, where the autopilot will go from whatever mode into this XTE cross-track error.

Gotta go,
Corwin
 
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