Can you feel your sails flog through the deck?

[Downeaster]

Test sailed a 46', higher end monohull production boat. Fractional rig with tacking jib. In 20 kt gusts you could feel a bit of a 'shudder' in the deck (cockpit seats and sole) when the jib was loaded but flogging a bit when as sheeting in. Beating hard on the wind. Didn't seem to happen every time.

Not sure what to make of this? My 35' didn't have this phenomena but this is a much bigger boat with much larger sails and rig. Maybe not uncommon for larger rigs given the loading? Any thoughts?

[boatman61]

Keel or deck stepped mast.???
Keel stepped will transmit more vibrations than a deck stepped mast.

[Downeaster]

Deck stepped...

[sguerrero1971]

We have a 42 Hunter Passage and this is pretty common on our boat. Ours is deck stepped and we have a masthead rigged jib. We also sailed a Mantus 42 Cat with a self tacking fractional rigged jib and it did the same thing.

Honestly it is one of the ways I know I need to trim the sails or adjust the Leech lines.

[boatman61]

Originally Posted by Downeaster

Deck stepped...

In that case I'd put it down to an unfamiliar boat and slower responses.. also with a self tacker one has the sail track slide on the foredeck being flogged instead of just the sheets in the cockpit .. but feeling flogging sails is a good thing..
When solo or shorthanded they wake me if I am asleep and I go up to adjust the sail or alter course if needed by the wind shift.

[Bill O]

Originally Posted by Downeaster

Test sailed a 46', higher end monohull production boat. Fractional rig with tacking jib. In 20 kt gusts you could feel a bit of a 'shudder' in the deck (cockpit seats and sole) when the jib was loaded but flogging a bit when as sheeting in. Beating hard on the wind. Didn't seem to happen every time. Any thoughts?

More sail trim needed? Would like to see the set up, but seems w/the self tacking the sheeting leads are set. Therefore need to adjust leech and foot lines to reduce flutter/excessive flogging and compensate for inability to move the car leads for the different points of sail.

Again much depends on the equipment including sail age and cut. Could be more than just the headsail causing the shutter. Did the rig have a forward jumper on the mast?

[wingssail]

Originally Posted by Downeaster

Test sailed a 46', higher end monohull production boat. Fractional rig with tacking jib. In 20 kt gusts you could feel a bit of a 'shudder' in the deck (cockpit seats and sole) when the jib was loaded but flogging a bit when as sheeting in. Beating hard on the wind. Didn't seem to happen every time.

Not sure what to make of this? My 35' didn't have this phenomena but this is a much bigger boat with much larger sails and rig. Maybe not uncommon for larger rigs given the loading? Any thoughts?

It wouldn't surprise me or disturb me if I could feel the fluttering of the jib while completing a tack. Most likely this new boat is transmitting the shaking through to the hull and deck. A self tacking jib, being short on span, will flog or flutter more than the big genoa on an older boat. (a small flag will flutter more, at a higher frequency, than a large banner will, right?).

Complete the tack quickly and the flogging will be reduced.

Why are you "sheeting in" if the jib is self tacking?

[Downeaster]

Originally Posted by Bill O

More sail trim needed? Would like to see the set up, but seems w/the self tacking the sheeting leads are set. Therefore need to adjust leech and foot lines to reduce flutter/excessive flogging and compensate for inability to move the car leads for the different points of sail.

Again much depends on the equipment including sail age and cut. Could be more than just the headsail causing the shutter. Did the rig have a forward jumper on the mast?

Thanks for the response. The shudder (very slight by the way) was just a couple times as the jib was being trimmed in. So the sails were fine. Sounds like it may not be too unusual.

I just had not felt that before on my 35' Catalina but maybe its just the much larger forces associated with a 46' boat with a pretty big rig. Anyone out there with a larger monohull NOT feel some light shuddering when the sails are flogging a bit?

[Downeaster]

Originally Posted by wingssail

It wouldn't surprise me or disturb me if I could feel the fluttering of the jib while completing a tack. Most likely this new boat is transmitting the shaking through to the hull and deck. A self tacking jib, being short on span, will flog or flutter more than the big genoa on an older boat. (a small flag will flutter more, at a higher frequency, than a large banner will, right?).

Complete the tack quickly and the flogging will be reduced.

Why are you "sheeting in" if the jib is self tacking?

That makes perfect sense - thank you. Ha - good question, I was tacking from a reach on one of the occasions. For beating - and I have to say - the self tacking was amazing.

[barnakiel]

Well if I could feel this in a 72' Oyster, probably a common thing in many boats?


b.

[roland stockham]

Yes you should and it is good, you need to be able to 'feel' the boat even below decks.

[Cheechako]

I think yes, you feel that shudder at times.
It often means you need to change the fairlead, or trim different etc.
Sometimes rig tuning/adjustment is indicated.
Or a sail with a blown out leech is the culprit.
Maybe rarely some of those rigs with limited stays may be an issue. Not entirely sure.

[Clivevon]

Yes. On my 36 ft boat if the genoa is flogging, worst case the whole boat can shake... Best to avoid.

[Clivevon]

and renew your forestay more often than the rest of the standing rigging maybe?

[Downeaster]

Everyone - thank you for the great responses and insights.

My summary is that this seems to be a normal phenomenon - perhaps amplified by the self-tacking jib which was probably banging the end of its track before settling down. And more pronounced with the larger sail and rig compared to my old (smaller) boat.

Cheers...