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Catalina/Capri 25/250 Sailor's Forums

Catalina 250 Specific Forum

Bow Weight

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Steve Blackburn
Master Marine Consultant

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Canada
1091 Posts

Initially Posted - 07/10/2008 : 09:55:33

I have been reading quite a few posts on adding weight to the bow. I'm still having problems docking. When turning into my slip, my bow drifts away with the lightest breeze (and I really mean light, you can barely feel it). When initiating my turn into my slip at about 1 knot and with the keel down, I get the bow exactly where I want it but continuing the turn both bow and aft keep moving and the boat literally moves sideways. Do you believe putting weight in my WB bow would tend to pin down the bow and let me maneuver the boat by sliding the aft left or right as intended? The technical purpose of putting weight in the bow evades me at this point.

Steve Blackburn, Calgary, AB
C250WB - 1999 - Hull 396

Edited by - on

Nautiduck
Master Marine Consultant

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USA
3704 Posts

Response Posted - 07/10/2008 : 14:18:45

I put 275lbs of rock in the bow (plus 16lb anchor, 25' chain, 300' rode) to accomplish four things:

1-Get her on her lines, level, so as not to have boat-induced mast rake.

2-Make the nose heavier for a better "grip" on the water. I want the sharp edge of the bow deeper.

3-Overall steadier ride due to more weight. The boat just feels more solid after adding the weight up front.

4-Reduce weather helm.

Edited by - Nautiduck on 07/10/2008 17:32:09

JohnMD
Navigator

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USA
207 Posts

Response Posted - 07/10/2008 : 16:31:57

Not to suggest the obvious, but, before you go to all the trouble of filling your bow with rock or gravel or whatever, you might get a couple of 'healthy' adults to sit up on the bow and see if your boat handles differently. It's a lot easier to remove them than it is the gravel.

Edited by - on

Steve Blackburn
Master Marine Consultant

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Canada
1091 Posts

Response Posted - 07/10/2008 : 17:50:42

Excellent idea John. Not "obvious" to me at the time.

Edited by - on

Arlyn Stewart
Master Marine Consultant

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USA
2980 Posts

Response Posted - 07/10/2008 : 18:28:25

Raking the mast fore/aft has the effect of balancing a sail plan to the Center of Lateral Resistance to neutralize the helm. Trimming the boat to her water lines by weighting the bow has some effect of raking the mast forward but that is not the dynamic at play with the 250.

The 250 suffers what I have called "Monster Weather Helm" but only when she heels excessively. The cause is not a sail plan balance issue. As with all sail boats, the mast rake should be trimmed so that when the boat is heeling at five degrees or so, it has only a slight weather helm. Raking the mast further forward will not cure the monster weather helm that shows up at 20 degrees of heel. It is caused by the asymmetrical foil section of the hull and specifically that the center of lift of that foil is too far aft and when it comes into play, it shifts the boats CLR significantly aft.

Trimming the bow down has the effect of moving the center of lift of the asymmetrical foil forward and closer to the boats normal CLR, thus negating much of the yaw force from the too far aft center of lift.

Now... regarding handling in a slip. The 250 hull form is designed for interior ballast and uses a hull form different than most center keel boats. Interior ballast requires greater hull form stability and a wider flatter hull is chosen with less rocker. Rocker refers to depth of the hull in her midsection. Boats with lots of rocker have a deeper midsection with lots of buoyancy gained by that mid boat depth. Boats with lots of rocker and a heavy center keel make great sailing and racing boats but they are notoriously uncomfortable in chop because they hobby horse so bad.

The 250 hull form (especially the water ballast version) is a very comfortable boat in a rough seaway. I've arrived at harbors on the Great Lakes after very nasty conditions passages and had skippers of much larger boats who had holed up for the day, shake their heads in disbelief that we embraced such conditions. There is a great difference in the comfort factor between a hobby horsing boat and a boat that reacts very much like a full keel boat.

There are however cost to pay for the virtue and one of them is handling. The flatter bottomed higher windage 250 struggles like keel boats when it comes to handling at slow speeds with a cross wind or current.

This is why engine thrusting is a must and hence why the soft link was born. As much as sailors with center keeled boats would like to weigh their experience in on this issue, they normally just don't get the dynamic differences between the 250 and other designs. They may even phoo phoo the need for motor thrusting. Don't listen to them. They don't know your hull form and the differences between it and what they have.

If you have not added a rudder-motor link and are not using motor thrusting... then the best tool available for reasonable docking is being missed.

Edited by - on

Steve Blackburn
Master Marine Consultant

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Canada
1091 Posts

Response Posted - 07/10/2008 : 19:40:25

Arlyn,

I was just thinking of your soft link VS the hard link design. As you know I was one of the original proponents for the hard link. The advantage of the soft link is that it will give you 10-15 degrees more freedom on both sides whereas the hard link is limited to the engines turn radius of about 90 degrees (45 on both sides). The extra degrees the soft link provides must make a great difference. When docking I arrive at about 1 knot with the engine engaged forward at idle. The problem is that I need to almost make a 90 degree turn on a dime type of turn or else I will hit my slip neighbor or the boats behind me if I try to take it wide. When turning into my slip I feel that I need just a little more turn on the tiller to achieve what I want. I know this because in the beginning of the season I had my engine straight with rudder unattached and when I was lucky enough to have the right speed and everything I could manuver the boat much better right when I needed to push the aft hard. I'm going to try your soft link idea and report back.

Thanks for the technical explaination, I now understand why I have such problems while others (with race boats) seems to do it so effortlessly (having nothing to do with experience). I can even see that they can afford a few mistakes while I cannot afford a single one from approach to being docked.

Edited by - on

delliottg
Former Mainsheet C250 Tech Editor

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USA
4479 Posts

Response Posted - 07/10/2008 : 22:55:12

Arlyn,
Thanks for such a succinct description of the handling problems with our boats and how the weight in the front helps.

As far as the hard link vs soft link question goes, I was a very big fan of the hard link I had with my old engine. It made a huge difference in handling the boat at low speed. With my new engine, I've come up with three separate hard link ideas and one soft link idea and rejected all of them as unworkable. The problem is the separation of the two centers of rotation in both the horizontal & vertical axes. I think I might be able to do a soft link if I extend an arm out backwards from my rudder, but it'll have to be extended so far that if I park the rudder to starboard, you won't be able to use the boarding ladder w/o dodging around it. I also think I might be able to go forward by extending the carry handle of the engine forward & linking to the tiller instead of the rudder. My first attempt at this failed, as did two attempts going back behind the tiller like my old hard link worked. I bent up several pieces of aluminum trying to make that work, tried flexible fiberglass rods (old battens from my catamaran), and various incarnations of wood, wire, bungees, etc. So far I'm stymied, the vertical difference makes it really hard to make it work, plus the vertical bars behind the fuel tank restrict movement. I'm thinking for this year about just making an extension to the carry handle that sticks up vertically so I can rotate the engine with it like an emeergency tiller arrangement, and cogitate on how to make either a hard or soft link work for a winter project for next year.

Edited by - on

frog0911
Master Marine Consultant

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USA
1349 Posts

Response Posted - 07/11/2008 : 09:35:29

Here is my setup for the soft link. I have the same problems you encounter, with the exception I don't hit other boats just run aground, but the soft link solved the problem.

Position when out of slip and cruising

Edited by - on

Steve Blackburn
Master Marine Consultant

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Canada
1091 Posts

Response Posted - 07/13/2008 : 20:09:33

Update. I finally resolved my docking problem. The problem was due to my lack of experience docking this boat. I was simply not turning soon enough. I have to initiate my full turn about 4' (seems to me from my point of view) before my bow lines up with the dock coming in at 1.5 knots (idling). It doesn't feel right at first as my instincts tell me to wait, but my logical side told me to go ahead and trust the theory. What happens is that after initiating my full turn, due to my low speed the boat doesn't react immediatly. It begings reacting about 3' later which is perfect. In fact I need to slack off on the turn slightly at some point so the manuver is a little forgiving. Little shot of reverse at the end and I'm docked like a pro.

Also noticed that if I miss my approach I can simply reverse the path I just came from. Before I was trying to reverse thrust and try to move the bow towards my slip but ended up too close to the boats behind me. So now the stress level is about 25% of what it was before because I know that if I miss just simple back off and the bow will follow pefectly.

Edited by - Steve Blackburn on 07/13/2008 20:12:35

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