1968 Aquasport Flatback Diver - Shipoke Rebuild for Hefner

[saltfly]

Great explanation of what a hook is. I’ll have to remember that, when trying to explain hull hooks to others. That’s also why I think it is important to support the hull and the transom with bunks. To prevent hooks from happening.  I never liked roller trailers for that reason. Traveling over the road and your boat bouncing up and down on rollers never appealed to me. I may be wrong, but I think you can never have enough support for your hull and transom.

[seabob4]

Hooks are like built in trim tabs.  The unfortunate thing is, sometimes we don't want to use our tabs!

Many times hooks are actually added to a running surface in an attempt to correct porpoising.  They can also be added to one side or another to offset a boat imbalance rather than add a bunch of lead to one side or the other.  The Proline 26 Express sports the exact same hull as the 26 Super Sport, with the addition of a hook on the starboard side to compensate for glass imbalance.  Between the cabin glass weight and the starboard helm station (as opposed to the centered helm on the SS), too much lead was required, hence, the hook.

Remember when I was at Hydra-Sports, they brought in a bigger boat (around 27) that porpoised like mad.  Added bigger Bennett tabs AND hooks on both sides...

But back to "unintended" hooks.  Gravity, as well as sunshine and weight, can straighten out a hull bottom.  The key is to "maintain" the intended bottom shape, such that when she starts to bend the other way, she doesn't go too far.  Just like fixing a twisted pulpit on a boat where either the hull or deck were pulled "green", in other words, too early from the molds, nothing to hold the shape anymore, usually exhibits that quality in a pulpit that is twisted to one side.  Deck the boat, and the whole pulpit is twisted.  There is a way to fix that little problem...

[Group W Bench]

Did you do something physical to manipulate the hook out or just rely on gravity?[/quote]

Bob,

Gravity will do the trick just fine if the stringers are removed. I think the same would hold true for rebuilds where the stringers are not removed. If not, just weight the inverted areas from the top with sandbags until the aft running surface is flat on a straightedge.

[Capt. Bob]

Bob,
Gravity will do the trick just fine if the stringers are removed. I think the same would hold true for rebuilds where the stringers are not removed. If not, just weight the inverted areas from the top with sandbags until the aft running surface is flat on a straightedge.

Ok then, after reading SB's post and your explanation, do you think that this condition (hook) could cause a hull like mine (WAC) to have a list to one side (port in this case) assuming that there is no additional weight as a contributing factor? This would explain my condition and is worth crawling underneath to take a look. Interesting stuff.
Thanks.

[wingtime]

Bob is the list while you are underway or just at rest?  I would think a hook would only affect the boat while underway since it would cause a deflection of the water flow much like a trim tab.

[saltfly]

A hook would only effect the boat while moving. You can check it very simply. I use a 6 foot straight edge, and lay it from the transom along the bottom. I let it stick out just a 1 inch. If there is a gap between the straight edge and the bottom near the transom. You have a hook. You need to check it all along the transom. I just, slide the straight edge along the bottom from port to starboard. Checking it as I go. You don't need to use a 6 foot stright edge. I use it just because I have it. Some just use a 2 foot square because they are only interested in what is happening at the transom. Also like bob. I’ve seen them added to do just what he said some do. But sometimes you don’t want to add one, because it won’t help with some problems. A friend, had a bass boat that would porpoise and chime walk.  The motor when trimmed up with the 21 pitch prop would cause it. Dealer told him to bring it in and they would add a hook to the hull. I told him it wouldn’t stop his problem. When trimmed up. The boat rode on the pad. A hook would only push the bow down. I told him to get a string ray hydro foil. We put it on the it did the trick. No more porpoise or chime walk.

[Capt. Bob]

List is while underway. She sits fine at rest. I noticed it when I did the sea trial a couple of years ago when I bought the boat but thought it may have been from weight distribution. Since then I have been conscious to loading placement with gear and people. Still rides port bow low but I correct with the tabs. Not a big deal but noticeable and not like either of the 170s or the CCP I have owned. I'll drag a straight edge over the underside of the hull and see what shows up.

Let's see if we can get this thread back to its author but thanks to GWB for the insight.

[gran398]

The author of the thread is Group W Bench.

[seabob4]

You're sorry, Scott...

A hook will present itself when underway at planing speeds.  I'd take a straight edge to both starboard and port, CB, see what you have.  I'd say it's pretty evident you'll find a hook or at least a bottom abnormality on starboard, but it would suck to fix that and then find starboard bow runs low...

[Capt. Bob]

The author of the thread is Group W Bench.

Bravo.
Still, this thread needs to get back to his original theme.Thanking him for insight while derailing felt like the decent thing to do.
Thanks for pointing it out though, as I only read the part about the "hook".  

[RickK]

Eugene, what are you using for resin?

[RickK]

Completed transom lam schedule is as follows:

3/4 oz mat
3 x 1708
3 x 3/4 oz mat (clamped between core and outer transom lams)
3/4" Penske, 3/4 oz mat, 3/4" Penske (1.5" core)
3 x 1708
3/4 oz mat

Remember that the hullside and bottom laminates extend w/ overlaps 6" into the outer skin laminates of the transom as well prior to clamping of the core. Easy and effective way to beef up the lam schedule.

Did you use the same visqueen, melamine and clamps approach here too that you used on the first layers supporting the outer skin?

[Group W Bench]

Rick,

The core is clamped to the transom with the same 5 clamps that we used for the melamine, but we don't use visquene. We just lay 3 x mat and wet out very thoroughly. The transom core should have 1/4 inch bleeder holes drilled every square foot or so. That way, you can actually see the resin weeping out of each hole to ensure that there are no voids. Torque clamps to ensure full bonding.

We use Reichold 344s resin on rebuilds.

[ashley]

Hey got these from Eugene today. Looks like ring deck has new core and glass.
Eugene- what is the core material?

[seabob4]

Now THAT is a donut deck!  If you saw my post from another thread, that, in the business, is what we call a donut deck, basically a rectangular "ring" that finishes off the topsides and provides the flange for the hull-to-deck joint.

Eugene's guys do it right, you can tell from the pic...  

And what's in the background, a Gheenoe rebuild?