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Can I make a bowsprit for my CP19?

Started by Lost Lake, January 08, 2008, 11:17:13 PM

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Lost Lake

Aren't they just stainless steel and wood with a downhaul to the winch eye? I bet if I saw one I could make one.

AdriftAtSea

It depends on what you want the bowsprit for and how well reinforced your bow winch eye is.

If you're planning on adding a bowsprit so that you can mount a sail to it, then you really need to work out how much force is going to be put on the sprit and build it accordingly.  A bobstay down to the winch eye will help, but you still need to build the bowsprit strong enough to deal with the forces involved. 

However, putting a sail on the bowsprit will move the center of effort forward and possibly leave your boat with serious lee helm or sail balance issues. 

If you just want to make a bowsprit to use as an anchor roller platform, then the bobstay to the winch eye is probably unnecessary.  Most of the forces on an anchor roller are downward and lateral, rather than upward.
s/v Pretty Gee
Telstar 28 Trimaran
Yet we get to know her, love her and be loved by her.... get to know about My Life With Gee at
http://blog.dankim.com/life-with-gee
The Scoot—click to find out more

Lost Lake

I'd like to move my genoa outside of my pulpit. I get plenty of weather helm now, I could use more leeward force.

The factory CP19 bowsprit comes with a new eye and bobstay (I'll never get all these terms memorized). I suppose it gathers all the strength it needs to resist down force such as me standing on it doing my 'Titanic Love Scene' maneuver from the steel straps running down the sides of the bowsprit onto the sides of the boat. Of course when the forestay is attached it will have plenty of strength, but when the forestay is removed the bobstay will be slack.

So is it as easy as cutting a fabulous piece of 2" thick laminated teak and wrapping a piece of 2" stainless around it and somehow attaching that to the boat (the pesky hull seam is right there).

I need to see one.... I think there's a couple of ComPacs in my state, and perhaps one of them have added the bowsprit. It was actually a stock item on the newer ComPacs, hey maybe I'll see one at the All Sail Show.   

Fortis

It is not "difficult" but it is mostly that way if you already know what your doing...Sorry, but that is the best way I can put it. Deceptively simple...is another.

There are issues with how you attach and bed in the eye at your bow, all sorts of strength capacity questions to ask and deciding just EXACTLY how long to make it, the boat may have too much weather helm at the moment...but that s better then too much lee helm later...so you need to find how to estimate the ideal balance point, because you are going to go through a lot of forestays testing for the best place otherwise.

The stainless bits are pretty simple, though doing it well is time consuming and you want to have the right tools. I guess your question boils down to "Yes, it is just some stainless and some timber and maybe some chain"....but that is just an ingredients list, not a recipe and not a meal.


Good luck.

Alex.


__________________________________
Being Hove to in a long gale is the most boring way of being terrified I know.  --Donald Hamilton

AdriftAtSea

If you can see how the factory did it... and get a chance to take some photos of it, that would probably be an excellent way to start.  If you can, look in the anchor locker as well as the forepeak, to see if they've done any under the deck reinforcing for the bowsprit. 

Also, if you get a chance, put something in the photo, so you can pull some fairly accurate measurements off of it. A Leatherman is often a good choice, since it does have a ruler on the back of the handle.  They've probably done much of the work of figuring how far forward the babystay and the new forestay attachment points should be, so why re-invent the wheel if you can avoid it.

The bowsprit needs to be attached in such a way to resist the forces the forestay will exert on it.  This is especially true if you're removing the old forestay.  If you're leaving the old forestay intact, it gives you a bit more leeway—and essentially leaves the boat with a Solent-type rig.  Often, the backing plate may be attached to the hull, to help the deck resist the forces created by the bowsprit and to help transfer the load to the hull, much like your current forestay chainplate is setup.

You might want to think about whether you want to make the bowsprit retractable, removable or permanent.  I have a retractable bowsprit on my boat, that extends about four feet.  The fact that it retracts is very convenient, and reduces the costs of the slip I have....since they charge by the foot.  A friend of mine has a bowsprit that attaches to where his bow roller mounts for when he is racing the boat, and doesn't require the anchor roller.

Anotherl thing to consider is whether you'll be using a tack pennant for the genoa or not. A tack pennant may allow you to use your existing sail.  It will also make it easier to see under the genoa, since it won't be sweeping the deck.  It will make handling the sail a bit easier, since the sail will clear the pulpit more easily with a tack pennant.  However, if you're using a roller furling/reefing unit, a tack pennant may pose a problem.

I hope this helps.
s/v Pretty Gee
Telstar 28 Trimaran
Yet we get to know her, love her and be loved by her.... get to know about My Life With Gee at
http://blog.dankim.com/life-with-gee
The Scoot—click to find out more

CapnK

The rough description of the CP 'sprit is about right. My CP23 had a retrofitted 'sprit, although it was factory made as far as I know. The details as I recall them:

Thickness was approx 1.5", and as best I could tell/recall the wood was solid teak planks, joined edgewise.

The stainless ran outside around the perimeter, and aft past the teak perhaps 6", with 2 thru-bolts per side that fastened to the deck lip above the hull/deck join (whisker straps, instead of whisker stays?).

The whole assembly was basically notched to accept the shape of the bow; it did not sit on the deck at all.

In the middle of the forward end of the 'sprit, welded to the stainless perimeter strap, was a vertical plate. This plate had holes (3 above and 1 below) to accept connectors for the forestay, foresail, and bobstay, with an additional reefing hook welded to the port side above.

The bobstay did connect to the towing eye; the eye was thru-bolted to a 4-6" stainless plate that rested against the stem.

The entire 'sprit assembly may have been 2.5' long, but was a little less than that, as I recall. I think the 'sprit added 11.5" to the LOA.

Lee helm was *not* a problem - weather helm was. I would have hated sailing that boat with no 'sprit! I don't think that adding a 'sprit will cause you any problems there whatsoever.

All this said, the single best improvement you can make to that boat is to get a foiled rudder blade from IdaSailor - it will improve the performance of the boat to such a degree that you will notice immediately that she steers better, has less weather helm, and points better/faster. Read this thread about that at the Com-Pac Owners website (if you haven't already). :)
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AdriftAtSea

capnK's being a bit modest, not mentioning his part in helping develop a foil-shaped rudder for the Compac series of boats. :)
s/v Pretty Gee
Telstar 28 Trimaran
Yet we get to know her, love her and be loved by her.... get to know about My Life With Gee at
http://blog.dankim.com/life-with-gee
The Scoot—click to find out more

Lost Lake

Quote from: AdriftAtSea on January 10, 2008, 09:19:43 AM
capnK's being a bit modest, not mentioning his part in helping develop a foil-shaped rudder for the Compac series of boats. :)

I know CapnK from the Compac site, and am familiar with his developing the foiled rudder. I can understand how the rudder being moved back a bit and being more hydrodynamic would be a great advantage having.

I thought maybe my CP was rigged wrong that I have such weather helm, but I guess that is the design. The bowsprit will help relieve some of that.

Now I just need to find one to photograph and measure. Do you remember if there is a support plate behind the eye or behind the 'whisker plates'?


AdriftAtSea

Did you check your mast rake.  If the mast is raked aft, that will generally contribute to weather helm. 
s/v Pretty Gee
Telstar 28 Trimaran
Yet we get to know her, love her and be loved by her.... get to know about My Life With Gee at
http://blog.dankim.com/life-with-gee
The Scoot—click to find out more

CapnK

Re: foiled rudder - it was something to do, that helped my boat, and was educational and fun. I'm glad that someone like Joel is the person who produces them now - he's a great guy, very responsive to his customers. :)

Mast rake - check that, with the trailerable mast it is easy to have too much.

Backing plates - there was one for the eye, and IIRC just big washers on the straps.
http://sailfar.net
Please Buy My Boats. ;)

Lost Lake

Thanks CapnK!  I asked about it on the Compac site also. I'll keep an eye out for pictures.