Finally, recovering straight on a CLH trailer?

[Matthew P]

Hi Graham, I'm sorry your trailer dramas continue but thank you for sharing them as we can all learn.  Do you think the post failed because of the pressure/drag of the boat on the post while being towed or because of the stress when pulling the boat onto the trailer?

Matthew
BR20 Gladys 

[Graham W]

Difficult to say - the trip from home to Bala is bumpy and mountainous but I think the final crack only developed as I winched the boat off the trailer yesterday.  This puts the post under quite a lot of strain. 

Whatever the case, it shouldn't happen - imagine the fuss if VW's cars (taking a random example) developed a metal stress fault in normal if extended use with the potential to cause an accident.

PS To give CLH their due, they have immediately offered to courier me a replacement post base, arriving tomorrow.

[Matthew P]

Hi Graham,

Intriguing - I would have thought winching-on exerts a lot more stress than winching-off, especially if the bows stick on the first roller crossbeam.  I'm no metallurgist but if the crack spread progressively over time (not necessarily true fatigue) then there should be some evidence of corrosion history on the crack face.

Also, how tightly connected was the post at the bows? Was the strop long enough to allow the bows to float up and down against the face of the restraining bracket?  This is worth understanding because if the stress is from the boat moving horizontally (from winching-on/of or deceleration on tow) then I can see ways to simply reinforce the post.  If the stress is vertical  from the bows moving up and down relative to the trailer then in my view it should be allowed to float vertically so that the boat hull is not fighting flexing in the trailer frame. I think I originally learned this from Klaus. On the other hand the boat still needs to be attached so it cannot slide off backwards. 

Up to now I have relied on the winch strop and ratchet mechanism to stop the boat sliding off backwards.   Not shown is that I use a rubber bungy to hold the winch handle down against the ratchet but following your experience I'll think about a better way to arrange this. Maybe I'll attach a strong strap to the draw-bar well in front of the post and lead it back over the post to the bow U bolt at an oblique angle.  Has anyone else any thoughts on this?

BTW the photo shows the jockey wheel attached but after long experience of the naughtiness of jockey wheels and their enthusiasm for loosening their brackets I remove mine altogether and carry it in the car.  Less trailer weight too.

The other photo attached shows my current attachment system.  The main strap passes between the cockpit coming and the mast and in front of the cleats.  The logic for this is that this is the strongest part of the boat and the hull is supported close-by underneath.  Also this strap is lightly inclined forwards which helps restrain the boat from deceleration forces.  The rear strap is simply around the boat, firmly but not too tight, because it would be easy to crush the sides together. BTW I put one twist in the strap to stop it thrumming in the wind and the buckles on the driver's side so I can watch them loosen and detach in my wing mirror.  But this has not yet happened.

I notice an interesting neighbouring thread about repairing the gel-coat  mentions strap buckle damage. While on the topic Matt Newland suggested using the cutup windsurfer mast-sleeves to protect the hull from buckle scratches and pad the straps over the gunnels and although untidy this has worked well.

Not shown in the photos is a long strap I now pass around the hull (with one twist of course) to support the centre board so it is not straining the CB up-haul.

All above are unqualified suggestions, not recommendations and owners must use their own judgements as to safe operation of their boat and trailer or get qualified professional advice etc. etc.

I seem to have got in rant.  Sorry. 

Matthew
BR20 Gladys
 

[Peter Cockerton]

Graham

Looks like a bad weld from the images and with the start of the failure opening wider at the front the strain on the post applied from the rear. Like Mathew i rope off the winch winder to stop it undoing in transit, and also have a safety chain from the winch eye back to the post as a backup on the winch strap/winch. Never crossed my mind to consider the post weld failing and as a result both of my methods for securing the bow failing, and you have found evidence that it's a not unheard off.

Will implement Mathews idea of strapping the boat to the trailer between the cockpit coming and the mast and in front of the cleats, until now i have been lazy and only used a rear strap.

Informative post and response from Mathew

Peter

[Graham W]

Matthew, Peter,

I attach my winch line quite tightly to the bow in an attempt to stop the boat banging around quite as much as it does on country roads.  I'm wondering if the fact that my Dyneema winch line doesn't flex much, if at all, might be putting an additional strain on things.  I'm not giving it up though.

I've recently been following Matthew's suggestion of attaching a forward ratchet strap between the mast and the cockpit coaming.  I'm wondering if that was all that stopped the winch post shearing off in transit, thus allowing the boat to go through the back of the car.

On the subject of additional straps, I notice Matthew that your trailer lacks a middle keel roller that on CLH trailers supports the centreboard if it drops.

Peter, I think you're right about the bad weld.  According to Google, some trailer manufacturers class a failure of the weld at that point as normal wear and tear, which is astonishing.

When the replacement winch post arrives from CLH, I'm going to get it reinforced with an additional support at the front, angled in the opposite direction and clamped separately to the towing arm. Something like the attached.

[Bill Rollo]

Graham

Bad luck on your trailer. I don’t know whether you saw these at Southampton - if indeed you were there. The frame looked really robust although the post does not look particularly strong. There were some neat touches to them - submersible lighting boards and oil filled bearings with a transparent cap - which looked attractive to the amateur (me), all at a perfectly hideous cost. There continues to be a market opportunity!

http://www.vanclaes.com/standard/index.php/en/

Best wishes

Bill

[Graham W]

Bill,

They're better-looking and a lot more orange than most of the substandard stuff in the UK. How much approximately is perfectly hideous?

Interesting that they've gone for stainless.  A question for the metallurgists out there: is there a strength to weight advantage compared to galvanised and particularly to aluminium?  And I wonder how stainless their stainless is.

[Bill Rollo]

Graham

A cursory look at the website suggests 3-4K, but our boats don't fit exactly into any of their ready made options - e.g. minimum Gladius is 1000kg. An enquiry might do better.

Bill

[Graham W]

if the crack spread progressively over time (not necessarily true fatigue) then there should be some evidence of corrosion history on the crack face.

I think the attached shows exactly that - a crack that developed in the starboard front part of the weld, where there is rust (left side of the photo), and then much more recently cracked fully everywhere else except the port side (bottom of the photo), which hung on by a thread. If the winch post was flexing to port because of the crack, that might explain why the boat's stern was increasingly skewed to starboard on the trailer, a problem that first started to appear at Raid England last month.

Of possibly more interest is the debris in the middle of the picture.  Is that a detached skull, scattered ribs and semi-mummified body of a small dead rodent? If so, how on earth did it get there?

[Graham W]

Graham

A cursory look at the website suggests 3-4K, but our boats don't fit exactly into any of their ready made options - e.g. minimum Gladius is 1000kg. An enquiry might do better.

Bill

That's probably at least twice the price of a (very) bog standard galvanised job.

Here's a UK company that seems to be trying to make a different sort of trailer, more on US/Australian lines http://www.geckotrailers.co.uk.  They claim that their aluminium trailers are 35-40% lighter, which would save 80kg or more.  This would make an unbraked rig for the BR's feasible again, as the combined weight of boat and trailer would be well below 700kg. No doubt at significant cost.

[Matthew P]

Is that a detached skull, scattered ribs and semi-mummified body of a small dead rodent? If so, how on earth did it get there?
[/quote]

Looks to me like the remains of Batus Craicus in which case you could find yourself in jail for 6 months and/or a £5,000 fine for disturbing a protected bat species nest site, Graham.

Matthew
BR20 Gladys

[Graham W]

Is that the one that carries rabies?

[Matthew P]

No doubt our medical acquaintances will confirm or correct for me - but I think you are confusing rabies symptoms of rage and extreme thirst with CLH misaligned boat syndrome.

Matthew

[David Hudson]

Just its belongings in a red and white spotted hankie on a pole.

[Matthew P]

Quote from Graham:
"I think the attached shows exactly that - a crack that developed in the starboard front part of the weld, where there is rust (left side of the photo), and then much more recently cracked fully everywhere else except the port side (bottom of the photo), which hung on by a thread. If the winch post was flexing to port because of the crack, that might explain why the boat's stern was increasingly skewed to starboard on the trailer, a problem that first started to appear at Raid England last month."
[/quote]

Bat, eh sorry, back to reality. If weld failure started at the front it suggests that the original stress occurred from pulling the boat onto the trailer.  If the bow got stuck on the roller swinging beam then this could be the root cause - in which case the solution is to overcome the bow-stuck-on-beam problem.  I've not had this problem with Gladys (she has given me other ones though!).  I wonder if the rollers on the swinging beam should be closer together and also is it possible to raise the front of the trailer, and hence lower the rollers, when hauling the bows over the beam?  Next time we meet it might be interesting to compare trailer geometries.

Maybe not quite to the point, my original roller had a very low ground clearance and I caught it hard on a sharp sleeping policeman on the Bala campsite nearest the sailing club.  Result was a broken beam, so I had a new one made which I redesigned slightly to have higher pivot points and hence more ground clearance. At the same time I made the vee a slightly sharper angle and possibly moved the rollers closer together.  It seems to work OK and campsite policemen can sleep undisturbed by Gladys. 

Matthew
BR20 Gladys

Please note - I'm not an expert and the above are personal opinions, not recommendations - readers should use their own judgement or get professional advice.