Seakeeping ability

[jclays]

To those with the 38/42 LRC How do these trawlers handle a large 5ft+ following sea?
Thanks

 

[TJM]

We are in a 41' President Trawler and a following sea is just not fun. It wreaks havoc with the autopilot to maintain a steady course, the speed of the waves is frequently faster than your 8kts travel speed. We would chose another destination for that evening, lol.

 

[Comodave]

I don’t know of any semi displacement boat that handles waves like that well. A full displacement hull would be better. It is all trade offs. Our President 41 doesn’t like them but it certainly can handle the waves. Actually it is my wife that doesn’t like them...

 

[rslifkin]

For the most part, with a wide, flat transom and small-ish rudders, the best defense against big following seas is bigger engines. That said, not all such boats are terribly behaved, but most are at least a decent bit of work at the helm if the waves are moving faster than you are.

 

[DavidM]

I recall a conversation I had with Bill Crealock, the deceased designer of most of the Pacific Seacraft line of sail boats. I asked him why most of his designs featured a canoe stern. His answer is that sometimes a stern needs to act like a bow.

The canoe stern is a bit of an extreme solution for a trawler, but Willards do it and I bet they handle following seas pretty well. OTOH our Mainship 34T which has a very wide beam aft handles following seas rather badly. But to TJM's point above, adding the gyro feature to the autopilot smoothed out the S turns significantly.

So in any case I think that the beam to length ratio at the stern is a pretty good predictor of how a boat handles in a following sea. My thanks to Bill Crealock.

David

 

[rslifkin]

A narrower, pointier stern definitely gets pushed around enough. With a wide transom, it's a matter of being able to correct for the pushing enough (big rudder and fast response, especially if on autopilot where it can't predict movement, only react). Or just go fast enough that you're not getting pushed around, but that's not an option for most trawlers.

 

[Nomad Willy]

For the most part, with a wide, flat transom and small-ish rudders, the best defense against big following seas is bigger engines. That said, not all such boats are terribly behaved, but most are at least a decent bit of work at the helm if the waves are moving faster than you are.

Bigger engines if you’ve got a good sized rudder to work w your big engine wash.
But big engines are for speed and at speed one needs a small rudder.
Fight the 5 footers or stay out of them.

Or placard it for 7 knots and/or put a bigger rudder on. But only going 7 knots you should only have half the power. Get a different boat or just fight it.

rslifkin states it nicely. As always

 

[rslifkin]

Bigger engines if you’ve got a good sized rudder to work w your big engine wash.
But big engines are for speed and at speed one needs a small rudder.
Fight the 5 footers or stay out of them.

Or placard it for 7 knots and/or put a bigger rudder on. But only going 7 knots you should only have half the power. Get a different boat or just fight it.

rslifkin states it nicely. As always

If you're going fast enough to need the small rudders, you're probably going fast enough to pace or outrun the waves. Then it starts to take far less rudder input to keep things sorted (being that the big transom isn't getting pushed on). It's tough to beat the feeling of climbing up a big wave on a slow plane, then accelerating 7+ kts as you surf down the other side with just a light touch on the helm (in a boat that's well behaved under these conditions).

 

[FoxtrotCharlie]

I don’t know of any semi displacement boat that handles waves like that well. A full displacement hull would be better. It is all trade offs. Our President 41 doesn’t like them but it certainly can handle the waves. Actually it is my wife that doesn’t like them...

Yep, most of our boats can take a lot more than we can.