Bowsprit 40cm off the center possible?

[CaptainRivet]

Hi all,

Can i mount a bowsprit off center by 40cm of the cat.
I have a welded on bow roller onto the crossmember of my Lavezzi. Assume they use the same crossmember for different cats as this bow roller is of no use on the Lavezzi, original anchor is set back at the bridgedeck. It also doesn’t line up with the windlass so i cannot use it for a 2nd anchor with a rope as the windlass has the rope gipsy on the other side and sits inside the locker.

As you can see in the foto that bow roller is offset by around 40cm from center of the cat.
I could simply take the roller out and use an aluminium or carbon pole and mount it to the bowroller, that would be much more sturdy then all this aftermarket bowsprits as the bowroller is welded to crossmember. Also can just use a pole i can buy here from from local inox wholersaler, less then 100Euro compared to eg the seldon bowsprit for>1000Euro which i need to mount to crossmember and drill lota whole in it. And well if i would need to.really use it i could take very quickly the bowsprit off and mountbthe roller.

I actually use that bowroller for the lower lone for the roundsail and cannot see any difference when running it via a block thats mounted at the center of the vessel.

[smj]

I would run it on center, but either way probably need a compression post running from forward crossbeam to the bridgedeck.

[Glenn C]

presumably bowsprits are mostly in tension ? considering that the load would be 40 cm off set from centre, then that would put a slightly lower bending load at that point on the cross beam than if it was centred. the loads on the anchor roller in a bouncy anchorage are probably lower than what you could expect on a bow sprit in high winds .

still rather than getting engineering advice from me, a boat builder could probably tell you straight away of any issues.

if it works seems like a good solution.

[CaptainRivet]

Originally Posted by Glenn C

presumably bowsprits are mostly in tension ? considering that the load would be 40 cm off set from centre, then that would put a slightly lower bending load at that point on the cross beam than if it was centred. the loads on the anchor roller in a bouncy anchorage are probably lower than what you could expect on a bow sprit in high winds .

still rather than getting engineering advice from me, a boat builder could probably tell you straight away of any issues.

if it works seems like a good solution.

The Lavezzi is heavily re-enforced, the crossmember mounting location at the hulls is 9 layers of 450g bi-axial mats with top notch binelester resin and then sandwiched in with 23cmx27cm SS chainplates 5mm thick. Not Lavezzi standard polyester resin and 4 times 5cm big washers
Flying since 2,5 years on the Lavezzi a round sail 8m diameter via the bowroller and spi-halyard up to 35kn gusting to 40+ and the heavy duty snapshackle connecting sail to lower rope rated for 3,5t (delivered by sail manufacturer and now replaced with a dyneema one) was bend so hard that I need the angle grinder to cut it open so the force that bowroller location can withstand much more then any lightwindsail on a bowsprit will ever produce.
The round sail creates a slightly upward pull as well and boatbuilder speced the re-enforcements accordingly so I can fly it till 40kn+ and then the sail will rip. Didn‘t thought of a bowsprit then.
Want a bowsprit mainly so I can better fly the Parasailor closer as kinda reacher from around 70 till 110 degrees.
The original bowsprit is mounted in the center but from underneath the crossmember and screwed to the massive „lip“ of the bridgedeck.
My plan is to mount the bowsprit the same way but from on top via the existing bowroller and rear to the bridgedeck lip.

The question what disadvantages or effects has that if the bowsprit is off center by 40cm on a 6,5m beam cat?

[CaptainRivet]

Thats how i plan it to do, how the original fixed CFK bowsprit is mounted and how the aftermarket does it on Lavezzi.

[Glenn C]

Yikes 40 knts, must have been interesting !

Not sure how much 40cm off centre would make sailing wise. presumably you would be able to sail closer to the wind on one tack compared to the other.

Are you able to mount the in board end of your pole slightly off centre the other way to the anchor roller, so that your forward end of the pole is closer to the centre line of the boat ?

[Glenn C]

PS, when I said the bow sprit would be in tension, I was thinking of a pole. A bow sprit would likely be in compression on the top and tension on the bottom. Maybe you need to consider the point loading on the bow sprit where it is pinned into the anchor roller fitting ? It might need some reinforcing at that pinch point ?

[toolbar]

I added an articulating bowsprite on the previous cat that was offset about 20cm on the front beam to clear the anchor, but centerline at the tip. Worked very well.

I second smj's point about looking into a compression post, especially when you think about running a screecher or something like that.

Another point to think of: when you use existing anchor roller from the pictures, the loads will not even go straight into beam, but push at a pretty strange angle (trying to shead the fitting off, instead of pushing it into the beam) unless you point the tip about 60 degrees up.

Bolting something to the beam is not too much extra work/cost, so I wouldn't fixate too hard on using the existing fitting.

Paul

[Tupaia]

If I remember correctly the A frame (seagull) striker on FP's is bolted (studs maybe), could you not take of the a-frame and sandwich a plate in-between to create a second articulated a-frame / bow sprit forward??


Having a fixed bowsprit can result in extra marina fees and would be a pia to remove, instead of fold out of the way.



I would think the offset forces of running from the existing bow roller could cause unforeseen issues.


By the time you have messed around with a pole, water stays and lower hull fixings a €1000 for factory item probably isn't that outrageous, but then it is also fixed, extra marina fees.

[CaptainRivet]

Originally Posted by Tupaia

If I remember correctly the A frame (seagull) striker on FP's is bolted (studs maybe), could you not take of the a-frame and sandwich a plate in-between to create a second articulated a-frame / bow sprit forward??


Having a fixed bowsprit can result in extra marina fees and would be a pia to remove, instead of fold out of the way.



I would think the offset forces of running from the existing bow roller could cause unforeseen issues.


By the time you have messed around with a pole, water stays and lower hull fixings a €1000 for factory item probably isn't that outrageous, but then it is also fixed, extra marina fees.

The factory item is crazy 12000Euro from FP and a CFK bowsprit.
The seldom aftermarket bowsprit is riveted with 8 or 16 rivets to the center of crossmember. 8 or 16 holes that weakens the 3.5mm thick crossmember exactly at the center where the highest load is plus the contact corrossion of the rivets, no chance to 100% isolate them with teff gel.
The anchor roller is welded to the crossmember very riged, so 1000 times stabler then this riveted on selden one but 40cm off center.

My planed bowsprit is removable, its just sticked in into the bridgedeck mounting and a bolt fixed it to the anchor roller and holding it in place. I need basically a 9cm diameter seawater resistant alupole 270cm long (50cm bowsprit) and the U-mounting piece and 3 bolts and ready is the bowsprit, can get all at local inox wholesaler for below 200Euro.
And thats the way many monohulls do their bowsprit, have 4 monos on my pontoon where its exactly done like this and the bowsprit pole goes instead of the 2nd anchor roller hold in place with the same bolt the roller was fitted and fixed at the rear end to deck with a u piece.
Yes i don't want to have a fixed one, noGo.

What do you guys mean with a compression post? The original design doesn't have one and mine is mounted like the original, just 40cm offset
How should this be installed, a picture or a quick drawing will be helpful.

[CaptainRivet]

Originally Posted by Glenn C

Yikes 40 knts, must have been interesting !

Not sure how much 40cm off centre would make sailing wise. presumably you would be able to sail closer to the wind on one tack compared to the other.

Are you able to mount the in board end of your pole slightly off centre the other way to the anchor roller, so that your forward end of the pole is closer to the centre line of the boat ?

I could bend the pole inwards so the front tip is closer to center. But its mainly for parasailor when going beam reach 90 degrees means parasailor flying nearly parallel to cat and not in front. And then its only important the bowsprit sticking out and moving the pulley for the 2 sheets from one bow 50cm more front, so the sheets also don't interfere with the seagull striker and genua stay, if its off center it doesn’t matter.

[toolbar]

See these pictures here for a good option for a retrofit (incidentally also offset).

https://forums.sailinganarchy.com/th.../#post-6825254

Four small fasteners to the beam IIRC - if positioned correctly these don't hold much, only keep everything in place, while the load goes directly into the fore-beam.

Keith / Boardhead is a nice guy, he probably either still has some parts ready or can make them for you and ship them from the US. If you find the right aluminum tube over here, you only need the end-parts, then shipping is cheap.

The bowsprit pushes back into the forebeam with considerable force, especially with a code-sail. The beam might bend backward and break. A compression post is basically another beam/tube running from the center of your forebeam to the front of your bridgedeck and keeps the fore-beam from bending.

Paul

[CaptainRivet]

Originally Posted by toolbar

See these pictures here for a good option for a retrofit (incidentally also offset).

https://forums.sailinganarchy.com/th.../#post-6825254

Four small fasteners to the beam IIRC - if positioned correctly these don't hold much, only keep everything in place, while the load goes directly into the fore-beam.

Keith / Boardhead is a nice guy, he probably either still has some parts ready or can make them for you and ship them from the US. If you find the right aluminum tube over here, you only need the end-parts, then shipping is cheap.

The bowsprit pushes back into the forebeam with considerable force, especially with a code-sail. The beam might bend backward and break. A compression post is basically another beam/tube running from the center of your forebeam to the front of your bridgedeck and keeps the fore-beam from bending.

Paul

Interesting and on his cat i can see why done like that and with 2m long bowsprit.
But why so complicated on mine, totally different mounting possibilities and the 2,7m pole in 8cm diameter is only 5kg in alu. His pole mounting location cannot support the loads, that's done by the tension lines, on mine the mounting points aka bow roller can easily take the resulting forces.
Look at the foto of my cat and my drawing how I plan and how the original bowsprit is mounted.
Here is a Lavezzi with the original bowsprit, in picture 12 you see exactly how it's set up.
https://es.boats.com/veleros/2003-fo...zi-40-9366633/
I use the same mounting point at the bridgedeck as original, original is mounted with 12 rivets to the underside of crossmember. I use the welded on bowroller which is 1000 time more rigid then original riveting and can transfer the loads into crossmember. Before that anchor roller mount sheers off the forestay mount or the seagull strikers would sheer before.
Original bowsprit has no supporting or tension lines eg going downwards to hulls, so why I should add any and make my live difficult when anchoring with the bridle when there is no need for them.
I don't need 2m bowsprit, I need 50 maybe 60cm max like the original bowsprit.

The bow roller is welded on full length and both side so that's more sturdy then any riveted solution that actually weakens the crossmember. I am building my own race cars incl. Roll cages since 30years so I have an idea of bracing and how loads are transfered and what stiffens and what weakens. Any upwards force on the tip of the bowsprit will be transfered into bridgedeck and partly into crossmember, same with side forces.
My only concern is the off-center installation.

[smj]

Originally Posted by CaptainRivet

Interesting and on his cat i can see why done like that and with 2m long bowsprit.
But why so complicated on mine, totally different mounting possibilities and the 2,7m pole in 8cm diameter is only 5kg in alu. His pole mounting location cannot support the loads, that's done by the tension lines, on mine the mounting points aka bow roller can easily take the resulting forces.
Look at the foto of my cat and my drawing how I plan and how the original bowsprit is mounted.
Here is a Lavezzi with the original bowsprit, in picture 12 you see exactly how it's set up.
https://es.boats.com/veleros/2003-fo...zi-40-9366633/
I use the same mounting point at the bridgedeck as original, original is mounted with 12 rivets to the underside of crossmember. I use the welded on bowroller which is 1000 time more rigid then original riveting and can transfer the loads into crossmember. Before that anchor roller mount sheers off the forestay mount or the seagull strikers would sheer before.
Original bowsprit has no supporting or tension lines eg going downwards to hulls, so why I should add any and make my live difficult when anchoring with the bridle when there is no need for them.
I don't need 2m bowsprit, I need 50 maybe 60cm max like the original bowsprit.

The bow roller is welded on full length and both side so that's more sturdy then any riveted solution that actually weakens the crossmember. I am building my own race cars incl. Roll cages since 30years so I have an idea of bracing and how loads are transfered and what stiffens and what weakens. Any upwards force on the tip of the bowsprit will be transfered into bridgedeck and partly into crossmember, same with side forces.
My only concern is the off-center installation.

Appears you have it all worked out.

[CaptainRivet]

Originally Posted by smj

Appears you have it all worked out.

It looks so simple and straight forward on the Lavezzi and the other FPs like Lipari (actually identical part no.) Or Belize, Bahia, orana.. with a similar style original bowsprit and this rigid but useless anchor roller but nobody done a bowsprit like this.
And i learned in boating if it looks so straight forward and simple but nobody done it till now there is a strong reason or killer argument why not. The 40cm offset from center?
It is not existing here or it wasn't mentioned till now...