Boom replacement with increased length.

[Airbus Nelson]

Hi
Looking for info please on replacing and slightly increasing boom length on Hustler 25.5.
Goose neck fitting on current boat requires replacement so consider it opportune time to replace and increase boom length with a view to increasing main sail size (and decreasing headsail size), so befitting a pocket cruiser. Considering loose footed main with area increase of perhaps 5-10%?
I would very much appreciate constructive feedback.
Thank you.

 

[mrming]

Ideally you end up with the centre of effort in the same place so you don’t add weatherhelm to the boat. I would start by talking to a local sailmaker to see if they would be willing to do the design calculations as part of supplying the new sails. Z Spars UK would be a good supplier for the new boom.

 

[Airbus Nelson]

Many thanks! Yes, have already contacted Z spars, as considered they may have 're-boomed' a Hustler 25.5 before.

 

[Dockhead]

I wouldn't do it, personally.

You will change the sail balance, and you will reduce the aspect ratio of the mainsail, which means you will get more heeling out of proportion to any increase in power.

Much better would be to invest in a roachy mainsail -- that will give you more power. If you can't increase the height of the mast.

 

[Dockhead]

Ideally you end up with the centre of effort in the same place so you don’t add weatherhelm to the boat. I would start by talking to a local sailmaker to see if they would be willing to do the design calculations as part of supplying the new sails. Z Spars UK would be a good supplier for the new boom.

If you lengthen the boom, and reduce the jib, you will definitely move the centre of effort abaft.

 

[mrming]

If you look at the drawing of the boat, you'll see there's not much scope for roach without a flicker. It was designed with a very large overlapping genoa so it's possible the designed centre of effort is further aft than it might immediately appear. I do agree there is a danger of ruining the boat's balance though, hence the calculations need to be done.

 

[Airbus Nelson]

Thanks all. Z spars have supplied replacement booms for the Hustler before, possibly not extended though. Sound reasoning against, I just wish to get away from the old IOR discipline.

 

[fredrussell]

If you lengthen the boom, and reduce the jib, you will definitely move the centre of effort abaft.

I see what you’re saying but wouldn’t making headsail smaller move that sail’s centre of effort forward? Larger mainsail foot, moving that sails centre of effort aft might possibly result in equalling the change in headsail c of e.

 

[Dockhead]

I see what you’re saying but wouldn’t making headsail smaller move that sail’s centre of effort forward? Larger mainsail foot, moving that sails centre of effort aft might possibly result in equalling the change in headsail c of e.

Not necessarily, because with less area, you also get less FORCE.

That being said -- reducing the overlap might well not cause balance problems. It's a very common modification to to replace those old 150% genoas with something more moderate. I don't personally like those large overlapping gennies at all; no good upwind, and no good once you start to reef them. On my own boat I alternate between a 120% yankee and a 95% blade, and there is no difference in balance. Higher aspect, less overlapping jib gives much less heeling moment, much less drag, with little loss of power in most conditions.

 

[Dockhead]

If you look at the drawing of the boat, you'll see there's not much scope for roach without a flicker. It was designed with a very large overlapping genoa so it's possible the designed centre of effort is further aft than it might immediately appear. I do agree there is a danger of ruining the boat's balance though, hence the calculations need to be done.

The way it's drawn, it has a very roachy, high aspect main:


That looks pretty nice. If the OP wants more power. the only really proper way to do that is to make the mast taller. That's an awfully big job -- new mast, all new standing rigging, new sails.

 

[Airbus Nelson]

Again, thank you so much all! I believe the previous owner did purchase a 'blade' and like Dockhead, I too loathe the huge overlapping genoas of that era. I'm going to speak with a sail maker this week with a view to a fully battened main and reduced area fore sail, as would befit what I hope will be, the ultimate pocket cruiser for the 'older' sailor. Certainly not looking for more power . Such great input!

 

[Airbus Nelson]

If you don't mind me asking Dockhead, what boat do you utilise a 120% yankee and 95% blade on? They appear pretty good figures.