How to design a bow roller

[webcraft]

.
Our Morgan Giles 30 needs a new double bow roller and forestay attachment and the local yard has offered to make us one using the existing singlge roller foreplate as a template.

I want to be able to keep our 9Kg Knox anchor on the bow roller. How do I go about designing a profile for one of the twin bow rollers that will accommodate that, keeping the anchor clear of the stem? Is there an easy way to mock up a template out of (eg) wood??


- W

 

[MM5AHO]

template of the bow, the roller or the anchor?

 

[lw395]

template of the bow, the roller or the anchor?

All three I should think?
I would probably start with some carboard, then make something out of MDF.
Or get an apprentoid to do it in a 3D CAD animation...

 

[Kelpie]

If needing a quick 3D model, Google sketchup is free and fairly simple.

 

[waynes world]

You seem to have answered your own question. Easy way to design/make a template is from wood.
As the previous replies have said, use a card first then transfer to ply/Hardboard of the likes.

 

[Wansworth]

Thick cardboard is easy to work and withjudicious glued supports a pattern an be knocked up

 

[Neeves]

There are 3 aspects. How to design a bow roller, how to design a bow roller that accepts a specific anchor and then how to combine all of this to fit your specific yacht.

If you check good bow rollers they have a rocker roller (a sort of seesaw) - as this reduces the load on the assembly when the anchor actually arrives at the roller. The rocker reduces the impact on the windlass as well. You can buy rollers off the shelf (Anchor Right make them - have a look at their website for ideas - but there lots of other suppliers). You might want to contact Knox and see what they suggest.

But cardboard, and then MDF.

Jonathan

 

[webcraft]

template of the bow, the roller or the anchor?

I want to stow the anchor on a bow roller that doesn't as yet exist so that the anchor does not foul the stemhead. Will have a play with the existing roller first.

- W

 

[BabaYaga]

If you check good bow rollers they have a rocker roller (a sort of seesaw) - as this reduces the load on the assembly when the anchor actually arrives at the roller. The rocker reduces the impact on the windlass as well.

You can achieve something similar by using two rollers (well, four for a double) where the forward, lower one is positioned at circa 45 deg. angle to the upper one.
I would be worried by a rocker making noise at anchor, but perhaps this is not a problem?

 

[simonfraser]

You can achieve something similar by using two rollers (well, four for a double) where the forward, lower one is positioned at circa 45 deg. angle to the upper one.
I would be worried by a rocker making noise at anchor, but perhaps this is not a problem?

re noise, use a bridle.

 

[doug748]

I want to stow the anchor on a bow roller that doesn't as yet exist so that the anchor does not foul the stemhead. Will have a play with the existing roller first.

- W

Don't over complicate things. All you have to do is establish how high, and how far forward your roller needs to be. Screw a bit of broom handle to a piece of 2 by 2 and experiment with the anchor and the existing single roller.

All the rest is detail that you can achieve off the boat.

 

[BabaYaga]

re noise, use a bridle.

Yes, but not so practical on a mixed rode, where the chain part is usually all in the water. If all chain, fine.

 

[awol]

A problem I would have had (but Knox have a solution) was a foul 'tween pulpit strut and anchor roll bar, otherwise the boat bow angle was compatible with the fluke/shank angle of the Knox.

 

[dgadee]

My Dehler bow roller was damaged (often happens due to poor material). I made up a simple template from plywood, set it in place and then held the anchor above it (tied). That told me what to change. Simple 2d drafting program gave me a file to take to laser cutter. He had a job on for 10mm stainless, so I went with that (£70), got the parts welded (£10), and glass bead blasted to look like original (£10). Holding it, it was like something off a battleship, but looks fine in place. The pontoon pylon I hit over the summer at speed suffered more damage than the roller.

 

[West Coast]

I had to modify the bow roller on my starlight when I got a rocna a few years back, used some grp plate to try different positions for the roller etc. Have a collection of photos I can send you if helpful, probably easier to email. Might give you some ideas. If interested, pm me your email address.

 

[Boo2]

A problem I would have had (but Knox have a solution) was a foul 'tween pulpit strut and anchor roll bar, otherwise the boat bow angle was compatible with the fluke/shank angle of the Knox.

What was Knox's solution, may I ask ?

Boo2

 

[kalanka]

This may not apply to your boat but I have had problems arising from the design and construction of my bow roller assembly which is on a kind of stubby steel bowsprit. There are two reinforcing bars which make a V shaped gap either side of the roller .

The boat shears around when retrieving chain in strongish winds and, when thirty degrees or so to the line, the chain jams rigidly in the V gaps. This is inconvenient and very bad for the windlass gears. Rebuilding to eliminate the V was far from simple.

Designing out the possibility of the chain jamming before it was constructed would have been a good idea!