c420 hull hook

While cleaning his hull my son noticed a hook in the last 24" of his c420 hull. All the hulls we looked at (15) from this manufacturer appear to have the hook. There are three other manufactures that do not appear to have a hook. The boats hold their own on the race course but I would think they be faster without it?

The deepest part is approx 6" from the transom and is approximately 3/16" deep.

My only experience is on small technical poling skiffs (back country, skinny water,flats boats). In most cases hook poses handling problems and is usually removed before delivery.

 

I think that happens when it shrinks in the mold. Less shrinkage at transom. I see it on lasers. I don't think it effects handling so much as not being ideal speed wise. It can be compensated for when the mold is made. I wouldn't dwell on it too much. Just have him and his crew spend some more time on the water and hit a few more regattas to make up for it. ;-) It's a great racing class. Very active.

 

Welcome to the forum.

Poorly fitted trailers also are a big hook maker. I make these types of repairs each year. Yes, it's not going to help, so iron out the hook, if interested in the best speed the boat can offer. Some will have you think you can push it out, but you really can't, unless you pile on a bunch of weight, just to prevent the hook from popping back.

'Glass has memory (so talk nice or it'll crap on 'ya) and if it's held in a position for long enough, it'll remember this position and you have to go to great pains to make it lose this sycophancy behavior.

Technically you can force it back into shape with braces, weights, etc., but it'll take a long time to remember it, even if you apply some heat (which does speed up the remembering process). The more economical way is to just fill it in. If it's deep enough, use some foam and bulk up the laminate, fair, smooth and paint. This method just repairs the hook. You can remove the hooked laminated on the inside if weight is an issue. In most cases you'll want as much laminate as the hull skin, so you can safely remove the puckered laminate from inside the boat (if you want).

 

Take care regarding your Club 420 Class Rules, specifically 7.2

7.0 Hull
7.1 Waxing, polishing and fine wet or dry sanding of the hull is permitted provided the effect is to polish only and not to fair or reshape the hull
7.2 Sanding or refinishing of the hull with the effect to lighten the hull or improve the performance, finish or shape beyond the original condition is not permitted. Repairs may be made provided the original hull shape is maintained.
7.3 The use of slowly soluble applications, that alter the boundary layer characteristics of the hull, is prohibited.
7.4 A protective strip or bumper may be added to or removed from the bow of the boat.
7.5 Additional inspection ports may be installed in the flotation tanks provided they are threaded. Bayonet closure mechanisms are prohibited.
7.6 Drainage capacity may be fitted into the lower transom in the form of one or two openings in order to drain the boat. The total area of the openings shall not exceed 80 sq. cm (12.4 sq inches), The openings shall have flaps or other closing devices that can be operated from inside the boat and shall not obstruct the rudder. One additional cleat or hook maybe installed on the keelson to provide a termination point for the control of the closing device.
7.7 One suction bailer and bailer accessories may be installed.
7.8 Only polyester resins may be used in the manufacturing of hulls after February 14, 2010.

www.navyleague.ca/_documents/.../CLUB_420_class_Rules-En.pdf

 

If the sailing club or local association is particularly worried about a repaired boat, they'll measure it, possibly using templates. The lines I have for the 420 don't show any hooks, just a sweet, clean, straight run.

 

I agree with all the above 100%, Thank you for the response. Jamie, you are right on the class rules; no modification allowed!

I guess my real question is how much does this condition hurt the speed of the hull.

I can only speculate that the bow would be pushed down when the boat is planing. There would be extra drag in displacement speeds but is it worth messing with.

 

Hard to say. I don't think you would notice it in terms of trim. You would just naturally move back a bit. I think the speed difference would be small, but another one of those cummulative things. I would worry about it at the national level, but not locally or regionally. There are always so many other things to focus on that you can fix. Make sure the rudder and centerboard are fair. Make sure the automatic bailer is flush and works well. Make sure the plastic trim around the centerboard where it exits the trunk is in good shape. Then of course all the usual stuff above the waterline.

If it is an old boat, and is scuffed up back there, that would be a good excuse to repair it. I would use a good marine fairing compound and one part polyurethane paint over that. As long as you are carefull lifting it with the dolly and loading it on the trailer that should do. As long as it is not a new boat that is otherwise superfast, I don't thing anyone would complain. If it is a new boat and the boys have been competing for awhile and are at the top of their game you might make inquiries about how this builders boat performs compared to others at the regional and national level.

I wouldn't hesitate to ask the builder about it. The molds should all be made from the same plug. The molds themselves shrink some when it cures, and then the boat will shrink some as it cures in the mold. Polyester shrinks more than epoxy and of course these boats and the molds as well probably are all polyester resin as they should be. Ask the builder about the difference and why they think it happens. Maybe the other builders use epoxy molds or heavier molds but that would surprise me. Maybe as PAR suggests it was the way they were stored after they came out of the mold. If there is a difference at the national or regional level and you are ranking in the top 10 regionally or nationally the thing to do would be to sell the boat and buy the other. They don't need to be new to be competitive, but if there is a functional difference that bothers you enough that would be the thing to do.

I like the Club 420 class. Very active and very affordable.
A bit heavy to launch and trailer, but hey, builds character. ;-)

 

To quantify the difference, if it is a really measureable dip I would say at the very most it would be in the range of 0.1% to 0.3% so over a 1 hour race, 4 to 12 seconds. It would depend alot on how hard it hooks right at the transom. You say 3/16" 6" from the transom. That would indicate a hook of about 3 degrees, assuming its an arc. But really if you naturally sit a little further forward upwind and downwind when not planing, and trim the boat to whatever feels fast when planing, I would the difference in speed would be buried in how well you are trimming your boat fore and aft in various conditions. So yeah, 3 to 12 seconds makes a difference at the National Level, but you would not be able to measure the difference by comparing the results of one manufacturer to another. Too many other variables even at that level.

It's a mental thing more than anything else. Yeah it would bug me but I would live with it and use it as an excuse to fair my foils and spend more time on the water. ;-)

p.s. If they fix it, I would tell them they have gained 15 to 60 seconds, but if they leave it, I would say they are only losing 3 to 12 seconds. ;-)

 

Are you sure that you are comparing C 420's to your boat and not looking at I 420 hulls? As I recall from being there at the time ('82-'83 I think), the whole reason there is now a "C" (Club or Collegiate; it changes over time) is the Vanguard boats didn't meet the international lines requirements because of production methods. So since they had already sold so many to sailing programs, they just "created" a whole new class, effectively only for the US.

 

It is definitely a C420. I am very familiar with the I420. I'm not sure what this has to do with the topic at hand.

 

My daughter and I raced one in Halifax this spring. She has just aged out of Optimists and will be racing Laser Radial, but also her Yngling on the river with friends, Club420 occasionally at the local club. She has volunteered this week to help out another club get their Optimist program up to speed. It helps to have someone her age show them the ropes and her enthusiasm for the boat. Up until now they have only had private laser radials and Club 420 there, but they now have six new optimists.

Best of luck with you son and his C420 racing. A friend of Margaret's races C420 actively in Nova Scotia and does a few regattas in New England. We might get down to Florida next winter for Laser and/or C420. I'm an old laser sailor. Maybe see you then.

Cheers.

 

Just pointing out that the form of a C420 hull is the same as a I420 hull except that it doesn't meet the lines accuracy because of the production methods. Hull fairness was one of the reasons IIRC. Just making sure that all the hulls you compared were real C420 hulls <shrug>.

 

I note there are three hull manufacturers for the Club 420 ( a class not seen here in the UK, only Int 420), all in the US. I would guess that even if all three hull moulds were originally off the same master plug, each builder has reinforced the mould in their own way. Also how that structure is supported in the'factory' may vary. Some small thing has allowed one mould to have a hook.

Whether it matters can only be decided by hard racing, especially two boat tuning over long distance say 1 mile on one tack or 2 mile runs side by side. There are differences in both Int 420 and Int 470 hulls (supposedly One Design) that are perfectly legal and make a difference. At the Int level, the boats have a racing life of about one year and some guys have been known to use a new jib each day of a Regatta.

The Club version I can understand, to help beef up these beasts for more normal traing and racing. Pity the Int version does not simply change their own rules and make the boats cheaper and more durable......

 

Excellent post. That's one of the good things about the C420 is that it is a heavier and stiffer hull, and a stiffer mast that is slower but required less rig tension to be fast, putting less strain on the hull. I420 and I470 turn into bananas as I understand it. Club 420s are slower but much cheaper to campaign, and very tactical. Lots of regattas within driving distance also, with very big fleets.

230 pound hull vs 180 pound hull as far as I know.

 

One other thing I did note was the layup resin. I'm not too familiar with the changes over the years but in the 80's, the UK Int 470(s) were definitely built using Vinylester resins, at least Cathy Fosters Olympic race winning one was. The C 420 rules definitely (post 2009) only allow unsaturated Polyester resin and no uni directional fabrics. So in some ways the Class has gone backwards, resulting in more delicate and shorter hull life.

Classes like the Lark - a College boat here in the UK - have generally become stiffer and more durable with one weight change over the near 50 year Class life (5Kg). Mind you we get spoilt in the UK because there are literally many tens of Classes to choose from. The slightly underpowered 420 is not one of my personal favourites, but has been selected as a Youth Class by the RYA. Partly because of the inherent massive costs involved to remain competitive. So your C420 makes a lot of sense.