Hook...Good or Bad????????
 

One for the bottom guys, I have a 236 Rinker Captiva. At 70mph it handles great with no problems. I put a straight edge on the bottom and there is about 1/8"-3/16" gap (hook) about 16" from the transom. What good or bad will come from removing this? and what kind of speed gain (if any) might I see. Thanks.

Re: Hook...Good or Bad????????
 

Monkey.. I am short on time... but I told a long story about hook a while back... maybe a long while back. Do a search and see if it comes up under my name as a post..
Took out too much hook on a 25' Checkmate and it caused some real problems.. It all depends on why the hook is there.. Usually 1/8" wont hurt anything and unless the bow is heavy.. wont help if it is removed.. if you need a bunch of trim to get the bow up.. It may help. How long was your straight edge... 6-10' should be checked to see the real story..

Hope this helps
Dick

Re: Hook...Good or Bad????????
 

Thanks, I will try the longer one. I am waiting on new Rev 4 23 prop to try. I seem to need alot of trim to carry the bow. This prop seems to be the magic cross between the B-1 and M+.

Re: Hook...Good or Bad????????
 

Hook will force the bow down.. If you can't carry it with a different prop, then maybe removing the hook will help.. it may also affect handling... Like I said see my story ...

Dick

Re: Hook...Good or Bad????????
 

The bottom has four lifting strakes. The two lower center ones stop 67" from the transom. The top two run full length. The keel pad starts way up front and ends at the transom about 5 1/4" wide. The boat leaps on plane, my buddys 22 Scarab will run right beside me, but I'll leave him 100 yards back from a hole shot. It looks as though if I take the transom down the bottom will then have a rocker in it. Would filling in the concave area be best? The strakes do not look to be sharp, more like a normal mold. The boat most likely weighs around 4400 with me and fuel. The motor has 521 hp at 5500 and 560 ft lbs from 4000-4400. It runs right around 70 at 4700 with a 25 m+ , 5000 with a 23 M+ I will be trying a 23 rev 4 hopefully tomorrow. The hp numbers were with dyno headers and no accessarys, so most likely somwhere around 475 at the prop.

Re: Hook...Good or Bad????????
 

My new boat has a slight hook in the last few inches of the hull and it is SUPPOSED to be there. I've heard of hooks being there that weren't suppose to from pulling the molds, trailers, etc. My boat is small and carries the bow decent but stays relatively flat. I could probably pull a couple more mph if I took it out but it would effect the handling of my boat and I don't want that. My boat needs no trim tabs at all in any water conditions. Runs and flies flat.

My blackhawk had rocker in the hull and going from the blackhawk to the Unlimited is night and day. Yeah, I lost a few mph but I've hit rollers and boat wakes in the Unlimited(which is 3' shorter) trimmed out at WFO that would have been DEADLY in my blackhawk. For a micro boat it tears chit up in rough water and I contribute a lot of that to the hook in the hull design.

If the hook isn't suppose to be there then remove it. If it is suppose to be there then I personally wouldn't.

Re: Hook...Good or Bad????????
 

Hook is designed into a hull for some of the purposes listed above, but mainly to achieve stable operation, free from porpoising. There are several ways to stop porpoising at a given speed:

1) shift weight forward
2) deflect trim tabs to give stern lift
3) put in hook to give stern lift
4) install a propeller with more stern lift
5) go faster (in some cases)

As most have probably noticed, at lower speeds (i.e. 40-60mph), you have to run your boat with more tab and/or lower drive trim to keep it from porposiing than you do at high speeds. As you go faster, you can trim it up more, which results in less wetted surface, and a center of pressure location farther aft. If your boat has a lot of hook in it, it means that it was designed to run with a CG position pretty far aft in relation to the intended speed (good for avoiding stuffing the nose). If you repower your boat, and want to go faster, you will benefit from taking some hook out, and you'll have to make up the difference at those lower speeds with tab position, but you'll pick up top end. The hook in the hull is more efficient at generating that stern lift than the tabs are.


Hope that helps, if you want more info on this, search through the archives for my screen name, and you'll find excerpts from a paper I published on the topic, in addition to lots of great discussion from some of the forum members.

Re: Hook...Good or Bad????????
 

I hate to sound like a wet blanket, but ......

I would just leave it alone. You are already going faster than that hull was ever intended to go. Hook or no hook, that hull is not very efficient if you are only going 70 with 521 HP. If speed is your goal, I would start by getting a fast hull.

Good luck,
Dave M.

Re: Hook...Good or Bad????????
 

i took a hook out of a 29 baja outlaw and all it did was porpus its as s off until it hit 70 then would calm down unless you trimed more then half way. also i didnt pick anything up.

Re: Hook...Good or Bad????????
 

You know boys, drag racing is my backround, and just when I started to think I had a handle on making things go fast....... :rolleyes: I always told my buddy, "Bottom Smottom" just make more power and the thing will fly! We went on a poker run on Seneca lake In N.Y., the water was really rough that day, 2-3 foot swells with alot of big rollers. While we got the snot pounded out of us, the boat handled well. Everyone should try riding the prop while the whole boat is out of the water, and climbing higher, :eek: at least once.(twice if your underpants are still clean after the first time) My buddy with the 22 Scarab had to slow down while I could keep going fast. Especially when his seat ripped out of the floor when he came down from one of the big rollers(god I wish I could have seen his face!) Thankfully we came home in one piece with a new appreciation for big water boating. I think I'm going to leave this boat alone. The Rev 4 prop I got today works exceptionally well. Brett at BBlades said I would love it and I do. While I don't have any gps numbers yet, it pegged the speedo back to the pin just like the 25+ did, and provided alot more bow lift while doing it. Thanks for the frank advice on the bottom. This place is great for getting both sides of an issue. Now if someone made an intercooler that sits on top of a carb in place of the flame arrester.....................HMM just thinking.

Re: Hook...Good or Bad????????
 

Just when I had myself talked out of it.....LOL.......What exactly is blueprinting the bottom? Taking the hook out and sharpening the strakes? Since you have done one I'm sure you have a handle on this.

Re: Hook...Good or Bad????????
 

Oh, and on the size of the boats, the guy with the 18' outboard put two 100 pound dumbells in the front. He turned back after the first stop.............

Re: Hook...Good or Bad????????
 

Why not? You just said yourself that you had a 236 running 85 mph in 2-4 footers!

Little boat + big water can be a lot of fun! :D

Re: Hook...Good or Bad????????
 

Art, is there a way I can get ahold of you? I would like to discuss the bottom with you a little more. I bought a Garmin gps today and got 67.9 at just under 5000 with the 23 REV 4. It was not a good air day, should pick up with less heat and humidity. Days like this we are off at least two tenths with the cars.

Re: Hook...Good or Bad????????
 

If your boat runs like a top and handles good, why mess with it?

Re: Hook...Good or Bad????????
 

That point is well taken, believe me I have not ordered the filler for the bottom yet. I went over the top with my Chevelle and got to the point where it was not enjoyable any more. It took all I had not to order heads when I built this motor. 521 with ported peanut port heads and 87 octane is making the most out of every cfm I can squeeze through them. I just thought that there might be some easy, relatively cheap gains to be had with the bottom. I bought this boat from the Insurance company after it had been partially sunk at the dock. Making the most without going overkill has been the plan the whole time, But being a speed junkie, you know theres always that little extra you might be able to find..........

Re: Hook...Good or Bad????????
 

Monkey, Had a 232 rinker with 454 power filled the hook area with eurosolft. Gave the boat 1.5MPH had a sports car feel with a slight porpoise.

Re: Hook...Good or Bad????????
 

Monkey..
when you blueprint the bottom.. you take a point 10' or so from the transom on the keel.. now draw two lines, from that point to each corner of the transom. This make a triangle. Hope that makes sense.
Anyway that area is the most likely to be the wetted surface and affect speed, handling, etc. You want it flat, sharp, and symetrical from side to side.
Some boats have hook built in.. to aid in planning and handling. I took out hook on my 25' Checkmate in the first two feet or so.. I didnt seem much of a change. Of course this was before GPS, so who knows??
Any way I proceeded to work my way forward and flattend about 6 feet of the center, there was sort of a pad on that hull.. Well all was good for a while. I would run 60 or so in 3 ft waves and all of a sudden a 4' would come along and pow.. the bow would point to the moon.. One time I came went up and tucked the steering wheel into my gut.. Hit the throttle hard to soften the landing, but I landed on the transom.. broke off a swim step.. Well from there it was trip and stuff.. well almost.
It kept doing it, everynow and then.. Violent reaction to one rogue wave.. I talked to a guy at the factory. He told me I took out too much hook.. Add some back in but do it out further.. I did and it worked great.. Except when I was on the river, I could feel the boat fighting the wedges I had added to the bottom.. out on the second strake, or between them rather.
Well ened up building tabs, moved them in and down close to the bottom.. When I was on Lake Mich.. tabs down 3/8".. fly ten feet in the air, but would fly flat.. On the river,, tabs up, go like H.... ..

So becareful.. It sounds like Cropfarmer has done it with one similar, without problems.. A flat bottom will go faster, but depends on what kind of boat, water, and boating you do..

Keep listening.. there is a ton of experience on this board. And have fun!! I hope you didnt sell the Chevelle.. I still have my 65 442 in the garage waiting till the boat thing settles.. it may be another 10 or so years. but it will wait..

Dick

Re: Hook...Good or Bad????????
 

Art, [email protected]

Re: Hook...Good or Bad????????
 

I know what you are saying. There are a couple of sayings that go along with this. If it ain't broke, your not trying. And the other case would be to keep fixing it till it's broke. Your boat sounds like it should be fun to take out and not really have to worry about.