Boat Handling and Slamming

I

ians

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Ok I have a sort of question for the panel

8 years ago I bough my first boat, it wasnt until we purchased our second boat a 1990 Fairline Targa 33 with twin diesels that we started doing any real journeys at sea and in tidal conditions where the boat could realy be opened up and enjoy the planning caperbilitys.
Now back in the early days I had a friend who basically tought me alot on boat handling and other general boating stuff, now some of his ethics I agreed with and some I didnt.
My friend did not realy go anyware at under 30 knots, well most of the time he was pretty much flat out.
We started off most of our boating down the humber which can get very choppy depending on the weather and does have a tendency to get short sharp waves.
Now on several trips down when it was like this and I noticed even after playing with trim angle and trim tabs that the boat would slam and make some rather horible noises.
I was told not to worry as my boat would take much more that I could ever take of punishment.
I didnt realy like this idea, and generally as a rule if the boat is slamming and cannot be adjusted it is time to slow down.

Our current boat a Targa 37 we tend to look after very well, as it has to last us and we have no intentions of changing until we reach retirement, which could be a good 5 years away(hopefully)

Now Targa 37s, and I have seen a few, have a tendency to have a problem under the galley seat were the bulkhead joins to the aft cabin bulkhead, this has always been a week point for some fibreglass splitting (its not structual), before we bought our boat, we noted that this had been repaired, and after a rough journey I had to repair it again 3 years ago (along with refitting fridge door and also several forward cabin doors which had departed)

So realy what I want to know is how does everybody else deal with this, does everybody slow down, or do people not worry about it so much.

Also can I ask. on shaft boats like Targa 43s etc, I have always had outdrive boats, do shaft drive boats suffer the same ?
The only experiance I have on a shaft boat was on a Princess 35 flybridge, and we went through some pretty bad conditions but sat on the flybridge I could not hear wether what was going on with the hull


any comments welcome

regards

ian
 
Ian

My general rule is that if it sounds bad it probably is.

My last boat would jump off waves and slam quite heavily, and this was always my cue to slow down, with my prime objective being to make progress without hurting the boat.

I really don't believe that you could go on pounding the hull without some fairly serious repercutions.

Finally I don't think drive type makes any difference, since it is more about hull design.

Neil
 
Thanks for reply Neil

Was not sure ref drive types, only thing I was not keen on with the flybridge was that I could not hear what was going on with the hull.
cruisers like ours you can hear it all !1

regards

ian
 
Think you would still feel it on the fly, if the P35 did slam. Which they dont do alot of. Shafts are definatly much better on the sea. Dunno if they all slam less than drives.

Answer is, not to let it slam, or as little as possible anyway. It's not good for you or the boat.
 
I've been in some hellish seas in the ten years since I bought her. Never seen a sea that she was not totally capable of, not that I was necessarily. But any boat will slam, if you try hard enough. Just slow down. 6 or 8 knots if needed.
 
Unless it's a following sea, trim the drives right in and put the trim tabs down. This will reduce bow lift and reduce slamming. If it still slams after that- Slow down!
In a following sea use drive trims only.
 
I suspect you will never stop it all. I'm a raggie & my boat slams in the right (wrong!) conditions. She is a bilge keeler so the amidships hull is pretty flat between the keels. Now this is not designed to come out of the water, but in shallow water wind over tide overfall conditions, the waves are so steep, short & confused that she will drop off the top of a wave into a trough from time to time.

It makes your ears ring (and your wallet wince) when she lands. No damage yet as the hull is about an inch thick at that point, but unpleasant to experience.
 
In my experience even the bigger boats slam when the sea state is wrong. I delivered several of the larger Princess motor yachts last year and even the P67 and 23M slammed if we went too fast into a steep sea. We just slowed down to the point where it stopped slamming... we certainly didn't just plough on allowing it to slam.

On one occasion I was at the help and allowed the boat to slam a couple of times and the airconditioning grill fell off the bulkhead chipping the lovely wood veneer work surface below... the skipper was none to pleased /forums/images/graemlins/blush.gif

It says more about the build quality of new Princesses than the quality of my helming though IMO /forums/images/graemlins/smile.gif
 
I think it is important for rough water to understand how the boat behaves and to know the planning speed,
lower the planning speed i will definitly slam less, this is part of the advantage of shafts, as some of the old shaft boats no prop pockets plan at 12 knots, shaft also have a more sticky attitude to the water then sterndrives so accept a 2 knot plus to a stern drive equivalent in a head sea. upwind situation

as for the slamming and what the boat can take, I have seen great damages to renowned builders who certify themselves as very good in rough weather conditions
so as someone said, if it does not sound good it is not
 
There is slamming and SLAMMING !! All depends upon what you consider 'bad'. Sharp bow entry means hard juddering, but when bow lifts and anything after 1/3rd from bow entry hits the next wave, you'd probably get a hard hit. You eigther have to force the bow down and let the bow do its best work cutting through the stuff, or slow down until you allow the hull to have 'natural' movement through the water. Alternatively you can vary your course to take the waves up to 45 degrees on the bow to increase the length of the waves and as such the ride becomes softer.

We are 45 ft long and deep V throughout (1.6M draft and 21T) ... and need at least 15-16 knots to achieve planning speeds, but after that she'll pound through most stuff until the waves allows the bow to lift too much and slamming occurs. After that is is back to 6 - 10 knots really and allow the hull to move naturally through the water at displacements speeds...... and yes, we have had some damage when the un-expected has occurred...
 
Hi Paul

No that was soft stuff up north, that yotti chap was taking the pee out of fairlines hehehe

Mite bring boat up to your place for few months beginning of next season.

Ians
 
Ash

can mabe do a deal, mabe you will need a bigger space soon, who knows

will see you at the weekend, hope river goods down a bit, its back in flood today , well it only August so what do we expect

ians
 
Alf

thanks for reply,
The targa is not too bad realy, basically I adjust the boat for the conditions, we came back from holland a few years back and the conditions were pretty bad, but it was posible to keep up just over 20 knots, and it was hard work as you had to work the boat round the waves pretty much like you said, and the ones you missed the eiree silence was followed buy a nice slam, followed buy fridge doors etc coming off !

Like you say if you have to slow down you slow down.

The pics you posted are fantastic, would like to have a chat to you sometimes for a bit of local knowlege ref top half of scotland.
We go on a range of 130 miles fuel supply for a journey, so up to the forth is no prob, but would like any info on harbours that would see me getting round to the start of your journey

Regards

ian
 
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