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Ken Surplice  
#1 Posted : 20 November 2018 23:33:47(UTC)
Rank: Advanced Member

Posts: 212
Location: Basingstoke, Hampshire

Hi Folks, it has been a while since keel roller and the rear keel shock block have been discussed. As Vol-au-vent is on land at present I am looking into both and would like to pool tips.

KEEL ROLLER

I refer to the front roller in the hull opposite the bottom of leading edge of the keel. Fortunately my roller assembly was easily removed with a ratchet and socket applied to the two hex head machine screws with captive nuts embedded in the hull. The bracket and roller popped out without fuss. Unfortunately, although I had replaced the plastic roller some years ago, there was a large flat on It. It is the same as other rollers pictured here on older posts and the same as I saw in another 275, Sophia. I have a rollerthat doesn't roll. I read earlier posts suggesting to use acetal instead of nylon but I expect They will go he same way.

Idea: replace the plastic roller with a metal roller then apply paint mixed with grit/sand to encourage the roller to turn against the keel. I also received advice to soak the assembly in melted anhydrous lanolin to prevent marine growth from preventing rolling. That said, my roller did spin freely, just not when the keel moved against its flat. A stainless roller is being made and I will share the result in a year.

REAR SHOCK BLOCK

I refer to the plastic block in the hull opposite the bottom of the trailing edge of the keel. This block was split after gently introducing the keel to some rocks during a spell of highh pressure. Live and learn. This block is mounted with two countersunk slot head machine screws. There are two captive nuts. So far so good. Unfortunately getting a purchase in the slotted heads was tricky and one of the captive nuts has become a free range nut. The thread turns but does not withdraw.

Idea. Replace the slot head machine screws with hex head machine screws. The extra drag will be minimal. Any thoughts on this?

Question. With the keel raised, no problem even with the front roller removed, I will reach around the spinning ex-captive nut and try to secure it. But how do I secure the nut permanently once more? Grease the thread and apply epoxy round the nut? All advice readily accepted.

Idea.3D print a replacement block. I don't have a 3D printer but read that such printers can accept acetal filament. While shaping a new block by hand is not difficult, the thought of 3D printing appeals to me. Did anyone try it?

Ken Surplice
philip linsell  
#2 Posted : 22 November 2018 09:04:02(UTC)
Rank: Advanced Member

Posts: 113
Location: CHICHESTER, west sussex

Hi Ken

The 26 does not have a roller, just a block, similar to the rear.

As your block is not turning it's acting in the same way as the 26 block.

If the keel goes up and down OK why not fit a block and stop fretting about non-turning rollers!

I know your keel is significantly heavier, but if it works.....

I don't see the need for grease etc, it's all water lubricated.

Philip

Ken Surplice  
#3 Posted : 25 November 2018 23:24:05(UTC)
Rank: Advanced Member

Posts: 212
Location: Basingstoke, Hampshire

Hi Philip,

I get your point and appreciate that my non-turning roller is effectively already a slider block as you describe. As I have already ordered a metal roller I feel compelled to at least try that for now. Thanks for sharing your thinking and definitely food for thought for haul-out 2019!

Ken Surplice
Ken Surplice  
#4 Posted : 04 December 2018 18:16:56(UTC)
Rank: Advanced Member

Posts: 212
Location: Basingstoke, Hampshire

Source of plastic block for aft keel buffer

I investigated where to buy a block of plastic to replace my aft keel buffer after it split during a grounding. Of all suppliers, a company trading on eBay offered by far the best value for money. 20mm thick white Delrin sheet cut to 80mm by 100mm cost £7.42 including postage. Delivery was prompt.

https://www.ebay.co.uk/i...k-or-white-/381988604726

Ken Surplice
Martin Watson  
#5 Posted : 29 December 2018 16:30:08(UTC)
Rank: Advanced Member

Posts: 74
Location: West Sussex

Hi Ken, I would urge caution in introducing two different metals under the water, ie, the stainless roller and the iron keel. Bi-metallic corrosion is very likely. If you have been using Acetal for the previous roller, you are aware that it swells in water? you should be using Delrin which was developed for use in water and is why it is widely used in the marine environment. As Phil has said, if it was working fine without turning, why not fit a fixed block a'la Super Seals and P27s and have done with it. It works for us so there is no reason it should not work for you. Ensinger in Waterlooville have offcuts of Delrin for only a few pounds if you go down to their warehouse, you are bound to find a suitable piece. I bought two large pieces as engine bearers for my boat because the engine mounts I was using were 30mm shorter than the old ones, they charged me £10. they were 30mm X 60mm X 400mm each. They have racks and racks of offcuts of all sizes, but you do need to visit, they don't sell offcuts by mail. Happy sailing!

Edited by user 29 December 2018 16:33:05(UTC)  | Reason: spelling error

Martin Watson
Martin Watson  
#6 Posted : 29 December 2018 16:40:10(UTC)
Rank: Advanced Member

Posts: 74
Location: West Sussex

PS, Ken, just saw you last post regarding source of Delrin, I think you'll find Ensinger is considerably cheaper than you were charged on Ebay!

Edited by user 29 December 2018 16:41:38(UTC)  | Reason: Not specified

Martin Watson
Ken Surplice  
#7 Posted : 07 January 2019 22:03:13(UTC)
Rank: Advanced Member

Posts: 212
Location: Basingstoke, Hampshire

Hi Martin, you are a mine of useful advice and information. This comes at a time when Vol-au-vent has finished her time ashore and is once more afloat ;-). Despite spending a good while on insulating the stainless steel bolts from my aluminium rudder stock, it did not occur to me to be on the alert concerning a stainless roller and the cast iron keel. While the paint on the leading edge of the keel inevitably wears away, leading to stainless to iron contact, I do recall that the keel clears the roller when it is up. We will see how it has progressed at next crane out.

Thanks for the tip on Delrin. I don't know what was in my roller before. I just know that it developed a flat. So in effect it was a slider and I could simply leave it to wear away further.

Cheers!

Ken Surplice
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