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Author Topic:   Proper Trim for Following Seas

jimh posted 08-13-2006 10:05 AM ET (US)
[The article which follows was originally appended to a very old discussion containing narratives of experiences in following seas. I have separated it from those narratives and moved it here to the PERFORMANCE section.]
Lagniappe posted 08-13-2006 01:37 AM ET (US)
I have question about trim in following seas, maybe for those more experienced than myself. I own an [unrecognized acronym used instead of model name--possibly means OUTRAGE 17].
When I end fishing in Lake Michigan mid afternoon, I return on easterly headings - which is almost always following seas, typically late afternoon kicks up somewhat and 3-4 seems a norm. Occasionally it can really kick up and have much larger seas and I have gotten sideways a couple of times, but recovered!
I feel I do good job, taking what the conditions dictate and "feel" of how the boat is tracking for my particular heading, speed, etc. I usually maintain speed to overtake the waves - if safe.
Sometimes I like how the boat is tracking with a little bow down, and sometimes conditions seem to favor a little bow up. I have not noted any pattern with wave heigth, period or angle of waves to the boat - that I believe exists to explain this since I am focused on driving!
Does anyone know why this may be, or if there is preferred trim given large following seas? Last week we had to do double time to beat an unforcasted and fierce storm.
john
deepwater posted 08-13-2006 09:57 AM ET (US)
I love my Montauk in long slow rolling 4' take me to the beach swells its like a 6' wide 17' long surfboard
jimh posted 08-13-2006 10:19 AM ET (US)
This first thing I would like to note is that when returning to the shore from offshore, the wave conditions are almost always a following sea. Wind driven waves will tend to bend and come ashore perpendicular to the shoreline. Even in the case where the wind is blowing parallel to the shoreline, waves will bend and come rolling into the shore, usually not more than about a 45° angle to the shore. About the only situation in which there will not be a following sea as you approach the shore is when the wind is blowing directly offshore. This usually gives calm conditions. The steepness of the waves coming ashore can be changed by the effect of current or tide, as well as by bottom shoaling. And all of these factors can combine to make the highest and steepest wave occur just at the mouth of an inlet or channel, producing the most hazardous conditions quite ironically just as the safety of the shore is about to be reached. But enough of that, let me answer the direct question about boat trim in following sea conditions.
When going downwind in a following sea, the usual situation is the boat is traveling faster than the waves. In this case I think the boat benefits from having a bow-high trim. This will keep the bow from plowing into the back of the next wave as you come down the face of the previous wave into the trough. It will also minimize any tendency to bow-steer, which you want to avoid in this situation. You do not want the boat to veer off course from the bow digging in when you accelerate down a wave face.
Running downwind in large waves can be quite fun in a classic Boston Whaler boat as the hull performs beautifully in these conditions. You have to modulate the engine throttle carefully. More power is needed to ascend the backs of large waves, and then, as soon as the boat comes over the wave crest, you have to quickly reduce throttle to avoid shooting down the wavefront.
If you are going downwind in a following sea and the waves are traveling faster than you, I can only guess at the optimum trim. My guess would be a neutral trim in order to avoid having the stern squat down and allow water to come aboard.
DANO posted 08-13-2006 10:25 AM ET (US)
John,
In my experiences with 44' MLB's in the Coast Guard as a Boatswains mate/heavy weather coxswain, you have to pick your boat attitude and stay on the same part of the wave. that is what you do on a surf boat. In your instance however, due to the ability to outrun your seas, you are most likely to rely on a constant retrimming to maintain safe hull attitude. On the ride up the swell you will want to trim the bow in somewhat to keep her on a decent plane while still nothaving the bow to high to get that dreaded "blowing over" feeling. on the downward side you are MOST assuredly going to want to trim a good ways out to keep the boww from digging in when you hit the bottom ( trough) of the wave you are skating down. Obviously when transitioning between going "up", going "down" and going back "up" again, prudent application of throttle and trim is essential. 1 hand for wheel, 1 hand for trim, 1 hand for throttle. Doesn't add up does it? Hence the reason for the throotle man on offshore race boats. In closing, you are doing an admirable job. you apparently feel the need for the trim adjustment and you have noticed the difference it makes, just continue to be careful but at the same time experiment. no one speed and trim is good for everyone, every boat and every instance. take care
dano
Buckda posted 08-14-2006 06:12 PM ET (US)
John -
Not sure what port you return to (did I see you yesterday fishing in the st. Joe river?), but when I return to port off lake Michigan when the seas are running, I always will slow down at the pierhead and "surf" the waves in, rather than power through them.
This means the boat is under "control" at all times, so I'm less likely to hit other boaters in the channel (or the piers), and it means that I violate the "no-wake" policy of the river at this point, though I've never been cited for this, since my wake is insignificant compared to the wave surge coming off the lake.
In St. Joseph, and depending on the weather, you may need to surf all the way to the Coast Guard station before the conditions allow you to reduce throttle to "no-wake" again without breaking waves running up your transom.
I like to run with a decidedly bow-up attitude when doing this, and typically there's quite a bit of foamy/frothy water about amidships when doing this.
Best regards,
Dave
Lagniappe posted 08-16-2006 11:53 PM ET (US)
Hi Dave,
No I was actually in Ludington helping my brother fine tune his tournement rig - its a big bulkly clunky Wellcraft, so he needs my help a lot ! :)
I usually launch from Holland or Grand Haven since I live nearby - but will trailer up the coast as far as traverse if the water is cold and the fish are on. Have never ventured south.., except for a few perch in S Haven.
Thanks guys, what I have learned is that I was trying to set trim and leave, and vary throttle. Since your posts I have already become comfortable adjusting both throttle and trim with each wave as needed. I guess I've been hesitant to overwork the trim system for fear of maintenance - not now. Recent trip, much more comfortable and safer working both actively !
john
Lagniappe posted 08-16-2006 11:59 PM ET (US)
P.S.
Dave, in Holland or Grand Haven - sometimes the boat wake is overwhelming with large waves coming from many unpredictable angles, and can dwarf a 4 following sea.
Not sure if I'm doing right, but still follow dad's advice from 30 years earlier (grew up boating in Pentwater area) - - trim up, moderate to medium speed, hold until into the channel...
john

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Author	Topic: Proper Trim for Following Seas
jimh	posted 08-13-2006 10:05 AM ET (US) [The article which follows was originally appended to a very old discussion containing narratives of experiences in following seas. I have separated it from those narratives and moved it here to the PERFORMANCE section.]
Lagniappe	posted 08-13-2006 01:37 AM ET (US) I have question about trim in following seas, maybe for those more experienced than myself. I own an [unrecognized acronym used instead of model name--possibly means OUTRAGE 17]. When I end fishing in Lake Michigan mid afternoon, I return on easterly headings - which is almost always following seas, typically late afternoon kicks up somewhat and 3-4 seems a norm. Occasionally it can really kick up and have much larger seas and I have gotten sideways a couple of times, but recovered! I feel I do good job, taking what the conditions dictate and "feel" of how the boat is tracking for my particular heading, speed, etc. I usually maintain speed to overtake the waves - if safe. Sometimes I like how the boat is tracking with a little bow down, and sometimes conditions seem to favor a little bow up. I have not noted any pattern with wave heigth, period or angle of waves to the boat - that I believe exists to explain this since I am focused on driving! Does anyone know why this may be, or if there is preferred trim given large following seas? Last week we had to do double time to beat an unforcasted and fierce storm. john
deepwater	posted 08-13-2006 09:57 AM ET (US) I love my Montauk in long slow rolling 4' take me to the beach swells its like a 6' wide 17' long surfboard
jimh	posted 08-13-2006 10:19 AM ET (US) This first thing I would like to note is that when returning to the shore from offshore, the wave conditions are almost always a following sea. Wind driven waves will tend to bend and come ashore perpendicular to the shoreline. Even in the case where the wind is blowing parallel to the shoreline, waves will bend and come rolling into the shore, usually not more than about a 45° angle to the shore. About the only situation in which there will not be a following sea as you approach the shore is when the wind is blowing directly offshore. This usually gives calm conditions. The steepness of the waves coming ashore can be changed by the effect of current or tide, as well as by bottom shoaling. And all of these factors can combine to make the highest and steepest wave occur just at the mouth of an inlet or channel, producing the most hazardous conditions quite ironically just as the safety of the shore is about to be reached. But enough of that, let me answer the direct question about boat trim in following sea conditions. When going downwind in a following sea, the usual situation is the boat is traveling faster than the waves. In this case I think the boat benefits from having a bow-high trim. This will keep the bow from plowing into the back of the next wave as you come down the face of the previous wave into the trough. It will also minimize any tendency to bow-steer, which you want to avoid in this situation. You do not want the boat to veer off course from the bow digging in when you accelerate down a wave face. Running downwind in large waves can be quite fun in a classic Boston Whaler boat as the hull performs beautifully in these conditions. You have to modulate the engine throttle carefully. More power is needed to ascend the backs of large waves, and then, as soon as the boat comes over the wave crest, you have to quickly reduce throttle to avoid shooting down the wavefront. If you are going downwind in a following sea and the waves are traveling faster than you, I can only guess at the optimum trim. My guess would be a neutral trim in order to avoid having the stern squat down and allow water to come aboard.
DANO	posted 08-13-2006 10:25 AM ET (US) John, In my experiences with 44' MLB's in the Coast Guard as a Boatswains mate/heavy weather coxswain, you have to pick your boat attitude and stay on the same part of the wave. that is what you do on a surf boat. In your instance however, due to the ability to outrun your seas, you are most likely to rely on a constant retrimming to maintain safe hull attitude. On the ride up the swell you will want to trim the bow in somewhat to keep her on a decent plane while still nothaving the bow to high to get that dreaded "blowing over" feeling. on the downward side you are MOST assuredly going to want to trim a good ways out to keep the boww from digging in when you hit the bottom ( trough) of the wave you are skating down. Obviously when transitioning between going "up", going "down" and going back "up" again, prudent application of throttle and trim is essential. 1 hand for wheel, 1 hand for trim, 1 hand for throttle. Doesn't add up does it? Hence the reason for the throotle man on offshore race boats. In closing, you are doing an admirable job. you apparently feel the need for the trim adjustment and you have noticed the difference it makes, just continue to be careful but at the same time experiment. no one speed and trim is good for everyone, every boat and every instance. take care dano
Buckda	posted 08-14-2006 06:12 PM ET (US) John - Not sure what port you return to (did I see you yesterday fishing in the st. Joe river?), but when I return to port off lake Michigan when the seas are running, I always will slow down at the pierhead and "surf" the waves in, rather than power through them. This means the boat is under "control" at all times, so I'm less likely to hit other boaters in the channel (or the piers), and it means that I violate the "no-wake" policy of the river at this point, though I've never been cited for this, since my wake is insignificant compared to the wave surge coming off the lake. In St. Joseph, and depending on the weather, you may need to surf all the way to the Coast Guard station before the conditions allow you to reduce throttle to "no-wake" again without breaking waves running up your transom. I like to run with a decidedly bow-up attitude when doing this, and typically there's quite a bit of foamy/frothy water about amidships when doing this. Best regards, Dave
Lagniappe	posted 08-16-2006 11:53 PM ET (US) Hi Dave, No I was actually in Ludington helping my brother fine tune his tournement rig - its a big bulkly clunky Wellcraft, so he needs my help a lot ! :) I usually launch from Holland or Grand Haven since I live nearby - but will trailer up the coast as far as traverse if the water is cold and the fish are on. Have never ventured south.., except for a few perch in S Haven. Thanks guys, what I have learned is that I was trying to set trim and leave, and vary throttle. Since your posts I have already become comfortable adjusting both throttle and trim with each wave as needed. I guess I've been hesitant to overwork the trim system for fear of maintenance - not now. Recent trip, much more comfortable and safer working both actively ! john
Lagniappe	posted 08-16-2006 11:59 PM ET (US) P.S. Dave, in Holland or Grand Haven - sometimes the boat wake is overwhelming with large waves coming from many unpredictable angles, and can dwarf a 4 following sea. Not sure if I'm doing right, but still follow dad's advice from 30 years earlier (grew up boating in Pentwater area) - - trim up, moderate to medium speed, hold until into the channel... john