Sagging Hog

[ARW123]

Some help please. My recently bought River Cruiser has a rather unwelcome sag aft of the keel and another pronounced dip round the rudder shaft. I advised that this is probably due to incorrect winter storage ie inadequate support; I also hav a suspicion that the replacement rudder about 20+ years ago is also much heavier than the original and has cotributed to the sagging around the shaft.





Question 1: is this possible to rectify by slowly increasing the degree of support a) in the medium term, b) over successive years c) not at all?

Question 2: Is there any chance of an insitu steamed solution? i.e. make up a steam box the encapsulates the hog (both inside and out and pump steam through for a few hours whilst VERY slowing increasing the lifting pressure from underneath).

The boat is extremely lightly made. She was designed that way, and derives much of her support from the water - more so than many other boats (she is 30' long). She is oak on oak; the hog is over a hundred years old and appears to be less than 2" thick by 6.75", the planking is about 30 years old.

[Jay Greer]

Often hogging can be traced to distortion of the deck panel. Look for any changes in deck crown in the area of the hogging. If the beams are bowed up and the width of beam slightly reduced in that area, that will be a clue as to whether or not corrective blocking in storage will assist in removing the hog.
Jay

[Peerie Maa]

Heat in the form of steam will not do it. The problem is most likely that as the support from buoyancy disappears aft, the boats weight continues, combined with poor support when ashore, most of the weight being carried on the fin.
Careful shoring back to shape over weeks or months may be attempted but avoid point loads. Run a plank for and aft either side of the rudder and place several shores under them. Tie these together with diagonals and then gently wedge the counter up, re tightening the wedges every week or so.
When she is back to shape take advice from a boat builder about fitting some tie rods to hold the counter up.

[Jay Greer]

The reason I mentioned checking or the distortion of the deck beams and narrowing of the hull is that, if the condition exists, it is doubtful that blocking the hull up will produce any beneficial correction. Then the only way to remove the hog would be to apply major surgery to the hull and deck.
Jay

[peter radclyffe]

Some help please. My recently bought River Cruiser has a rather unwelcome sag aft of the keel and another pronounced dip round the rudder shaft. I advised that this is probably due to incorrect winter storage ie inadequate support; I also hav a suspicion that the replacement rudder about 20+ years ago is also much heavier than the original and has cotributed to the sagging around the shaft.





Question 1: is this possible to rectify by slowly increasing the degree of support a) in the medium term, b) over successive years c) not at all?

Question 2: Is there any chance of an insitu steamed solution? i.e. make up a steam box the encapsulates the hog (both inside and out and pump steam through for a few hours whilst VERY slowing increasing the lifting pressure from underneath).

The boat is extremely lightly made. She was designed that way, and derives much of her support from the water - more so than many other boats (she is 30' long). She is oak on oak; the hog is over a hundred years old and appears to be less than 2" thick by 6.75", the planking is about 30 years old.

is this rudder the wrong way round

[ARW123]

...The problem is most likely that as the support from buoyancy disappears aft, the boats weight continues, combined with poor support when ashore...

I suspect the latter, since for the first 80 years of her life this sagging was not apparent.

Could you explain what you mean about the diagonals? is it to prevent the top ends sliding along any incline?

I suspect the boat will be out of the water for at least 6 months - do you think this period of time would achieve any noticeable results?

[ARW123]

Peter: Yes!

The trailer was originally for a 26' boat drawing 5' and had to be altered (mine is 30' and draws less than 3') as it is the 1st time she has ever been moved more than a couple of miles from the river system. Because I wanted to support the boat as close to the heavy rudder as possible, we had to swing through 180 degrees to achieve this. These little challenges will be ironed out as time elaspes.......I hope!

The old stern chock support can be seen just in front of what would be the trailing edge of the rudder. This may well be moved forwards a couple of inches to act as extra support in an effort to remove the distortion that was the subject of this post.

[Peerie Maa]

I suspect the latter, since for the first 80 years of her life this sagging was not apparent.

Could you explain what you mean about the diagonals? is it to prevent the top ends sliding along any incline?

I suspect the boat will be out of the water for at least 6 months - do you think this period of time would achieve any noticeable results?

Yes and yes. I meant light timber ties nailed on to keep everything in alignment. If she is to be out for six months, consider keeping the humidity stable. A clinker hull could split planks if they dry out.
Have a really good look at the structure, considering changes of shape, and opening joints as Jay suggests. Above all listen out for creaks and moans as you tighten the wedges, she will tell you if she is uncomfortable.

[ARW123]

...consider keeping the humidity stable...

Already in hand, Nick. I have quadruple layer of old carpet in the cockpit, dosed down twice a day with a hose and old sacks in the cabin, under seats and deck areas kept moist with a knapsack sprayer. All vents, hatches & doorways are kept open to prevent stagnation.

Reason for this extreme wetting regime is because for the next week she is outside; I'm waiting to get her in the barn...

[John Meachen]

All the advice in the thread is sensible and the precautions already under way are likely to help.I would be curious about whether there are any sound floor timbers in the vicinity of the rudder tube or whether the structure was altered when the rudder was replaced.The rudder looks pretty normal for a river cruiser,even if it has been temporarily reversed,and I have doubts as to whether it has added more than a few pounds.I suppose the only way to be sure would be to contact a previous owner or somebody familiar with the boat when it had its old rudder-which still may not have been the original.

[ARW123]

John: The original rudder sheered off under sail about 25 years ago and it had not been changed since my father had the boat in '46. I suspect it is unlikely that it had been replaced in the 40 years prior to that. The original was as light as a feather (to steer with); this one is a dog.

Ther rudder tube is poor at the base - galvanised and rusting. I am having the whole rudder and assembly replaced with a stainless version with bearings top & bottom (a conversion that I believe is very successful on Waveneys). There appears to be little any modification at the Water interface, support under the deck does appear relatively new however:

[peter radclyffe]

John: The original rudder sheered off under sail about 25 years ago and it had not been changed since my father had the boat in '46. I suspect it is unlikely that it had been replaced in the 40 years prior to that. The original was as light as a feather (to steer with); this one is a dog.

Ther rudder tube is poor at the base - galvanised and rusting. I am having the whole rudder and assembly replaced with a stainless version with bearings top & bottom (a conversion that I believe is very successful on Waveneys). There appears to be little any modification at the Water interface, support under the deck does appear relatively new however:

this boat is weak, if you can jack it back up, either way, you might want to consider fitting a new hog, 2 x 6 inch, before you make a new rudder gland

[ARW123]

Peter:

You'll forgive me for being a bit protective I hope - but "weak"??? The boat has survived 103 years!!

You recommend replacing the hog with a new one 1/16" thicker and 3/4" narrower; I'm having difficulty in seeing how that can be improving the strength - or am I missing something?

[peter radclyffe]

Peter:

You'll forgive me for being a bit protective I hope - but "weak"??? The boat has survived 103 years!!

You recommend replacing the hog with a new one 1/16" thicker and 3/4" narrower; I'm having difficulty in seeing how that can be improving the strength - or am I missing something?

excuse me, im not being clear, i mean put a second hog on top of the frames, a keelson