What is used to blueprint the bottom of the Hull

[63stevens]

What material is used to blueprint the bottom of the boat? What do they put on it to take out the hook and fill in the low spots?

[TRG]

i know im a jet owner, but i was informed that in my application, that you would use a product called "Marglass" wich you should not have a problem finding in most any A/B supply house!
although, back when i removed all of the hook from my hull... i was not aware of the HB site, so i went ahead and "glassed" in the hook...i did not have much at all (hook) but it was still alot of work!
i am very curious to know if there is any other methods as well?
todd

[BILLY.B]

Glass, Marglass, and even the high end bondo will work, (not the cheap stuff from Pep boys). I added some length to my strakes and made them out of Z-grip by Evercoat (bondo). It has been on there for 2 seasons and looks great. I went over the bondo with resin to seal it up and then speed coated the area. Marglass works great also, the bondo was just easier to shape for my situation. Just make sure to seal it up with resin.

[Jake W]

Alot of people use Rage Gold also sands easy and easy to work with.
Jake:D

[DUCKY]

All of these methods work well. I like to try and use whats already there. If you have a major hook, add more glass to the inside of the boat (so you don't go through) and air file the bottom until it's gone. That goes for sharpening the lifting strakes as well. Then just use filler as necessary and speedcoat, gel coat or prime for paint...... Just my opinion, but if your adding material to the outside of the hull to lose a hook, your just making the hook longer and less noticeable, not really removing it......

[BILLY.B]

Originally posted by DUCKY
but if your adding material to the outside of the hull to lose a hook, your just making the hook longer and less noticeable, not really removing it...... :confused: :confused:

[TRG]

is'nt the idea of removing hook,....to essentially, remove the hook, not move it around?
did i read that right?
no toe crunchin here!

[Cas]

here's a link to a pictorial essay of one of the guys in our club that removed the hook. In the pic labeled Blpnt3, you can literally see the hook he had
http://community.webshots.com/album/35860873JHJruE

[old rigger]

Originally posted by DUCKY
All of these methods work well. I like to try and use whats already there. If you have a major hook, add more glass to the inside of the boat (so you don't go through) and air file the bottom until it's gone. That goes for sharpening the lifting strakes as well. Then just use filler as necessary and speedcoat, gel coat or prime for paint...... Just my opinion, but if your adding material to the outside of the hull to lose a hook, your just making the hook longer and less noticeable, not really removing it......
Ducky,
I don't want to start a flaming thing here, but that's the wierdest advice I've ever read on this board. What are you talking about?
You mean to tell me that if a customer brings a boat to you to remove the hook, that's the way you do it? You'd pull the engine(goes with out saying) rip out the carpet, remove the floor and add glass to the inside? replace the floor, and carpet and then flip the boat. Then, you'd grind down the GOOD surface, the flat or straight one, you'd grind down that flat surface of the bottom to the same level as the DISTORTED one. Where the hook is? Thats insane. It doesn't even make sense.
What if a boat only has hook on one side and you fix it that way. Now one side of your boat has a different degree than the other side, because your way, you'd have to grind the bottom from somewhere in front of the dash to the transom to make it straight. What, would you go grind on the other side just to match what you've done to the first ??? You'd have to to make it right, but that's just wierd.
If you're adding material to the bottom of a boat, (which is the right way to do it) and you still have hook, or like you said, you've made the hook longer, you're not working a big enough area.
You can add material to the inside so you can grind rocker out. And I've added some material to boats down the keel, to grind in a delta pad in, but to remove hook? I dunno man, sounds crazy to me.
No offense, but if I took a boat to a shop to be worked on and that's how I was told it was going to be done, my truck, trailer and boat would be just a blur.

[BILLY.B]

Originally posted by old rigger
Thats insane. It doesn't even make sense.
If you're adding material to the bottom of a boat, (which is the right way to do it) and you still have hook, or like you said, you've made the hook longer, you're not working a big enough area.
I dunno man, sounds crazy to me.
Thats what i'm talking about....

[DaveA]

I think he's got hook and rocker mixed up...
I can see putting material in the bottom inside if you're gonna grind off the high spots on the bottom.
I just think he's got the two backwards, that's all.
Right, Ducky?

[DaveA]

That is, of course, that you don't have a core to contend with. If you grind off rocker (high spot) you run the risk of cutting into the core material- plywood/foam/balsa etc. So really building up the interior material (back side of the sandwich) won't help....IF you have a core in that area- which in these types of boats, I think you usually do, right?

[TRG]

if there was that much work to put into a hull....i think the hull would up for bidding!! but then again, i dont know that ive ever seen a hull that would need this much work either!
todd

[DUCKY]

Wow, I haven't been here in a couple days. I didn't know I was getting flamed all to hell. I hope this drawing helps to explain where I am coming from. Now granted, I don't do much of this type of work where I am now, but I have done it this way with great success. I did an early 70's Tahiti jet boat like this. It had a 1 1/8" hook in the last foot of the bottom. And the bottom was only about 5/8" thick. It was so bad that the hook could actually be seen on the inside of the boat. I added lots of glass to the inside, and removed the hook on the outside with a big ass grinder, and an air file. With no other changes, the boat was 9mph faster, and picked up 600rpm.
Now then I see where some of you guys are coming from as well. If the bottom was warped from say sitting on the trailer, then you could just fill it in, but if the hook was designed in (as many jet hulls were, before place diverters) It should be ground off.
http://www.***boat.com/image_center/data/503/776Scan0001-med.jpg

[BILLY.B]

Originally posted by DUCKY
Wow, I did an early 70's Tahiti jet boat like this. It had a 1 1/8" hook in the last foot of the bottom. That was the first problem, it was a Tahiti. Second, if it needed that much work i'm sure the labor charge would of out weighed the value of the boat itself. A friend of mine did his CVX 20 (Carlson, AKA James Bond style boat) the way I thought it sholud be done. Flipped the boat over, grinded the boat where the hook was (3/4" hook) and added glass to make it flat, and smoothed it over with bondo and a board file, we straight edge it to make sure she was straight , straightened the strakes and WHA-LA, 10 mph faster and all that without glassing the inside. And I do believe we didn't just move the hook around the bottom of the boat.

[DUCKY]

Originally posted by BILLY.B
That was the first problem, it was a Tahiti. Second, if it needed that much work i'm sure the labor charge would of out weighed the value of the boat itself. A friend of mine did his CVX 20 (Carlson, AKA James Bond style boat) the way I thought it sholud be done. Flipped the boat over, grinded the boat where the hook was (3/4" hook) and added glass to make it flat, and smoothed it over with bondo and a board file, we straight edge it to make sure she was straight , straightened the strakes and WHA-LA, 10 mph faster and all that without glassing the inside. And I do believe we didn't just move the hook around the bottom of the boat.
What can I say, the guy loved the boat! I think I charged him about $1500 to do that job, and he brought it in already stripped (no motor, no pump, no subfloor, etc.....) I also replaced one of his "half stringers" while I was at it. I scooped it out with my bare hand it was so rotten. And Billy, you are right, I could have done it all from the outside, but I felt It would be stronger that way. Was it? Who knows..... If I was to do the same job today, I would probably do it a little differently. I guess all that matters is that when you put a straightedge across it, it's flat...... How you get there is up to you.......

[old rigger]

Ducky,
Like I said, I wasn't flaming you, I just didn't understand why you did it that way.
I hate to tell you this, but Tahiti, or for that matter any other
so-cal shop I ever worked in, never added hook to the bottoms.
That's an old bullshit line that the salesmen came up with when dealing with the customers. They had to tell them something, and they couldn't tell them the truth....the part only sat in the mold for 8 hours, was pulled and then shoved out in the hot sun on a dolly for half a day. Or the rigger ****ed up the bottom of your boat cause he installed the intake wrong by tightening down like he was capping a well, or we just build a quick and dirty boat. Most people buying a Tahiti back then, didn't know or care about the hook in the boat. They just wanted to get on the water. Then they probably bought a better boat down the road. lol
Thank god there were so many boat shops that built boats like that (and there were MANY). Look how much biz it gives all you guys in the repair shops now.....
I had the 29th Tahiti made and even after 30 years, the bottom was arrow straight. There was a difference between the 60's Tahitis and the later ones. But really, who cares, they were always, no matter who owned the Tahiti shop, an entry level boat. The bottom on my old 16 was over an inch thick down the keel. I wish now I'd kept the little thing. It was an outboard.

[DUCKY]

It might not have been a Tahiti. That's just what popped into my head. It could have been a Caribbean, a Hawaiian, or ? But I have seen lots of boat bottoms (probably not as many as you, but still a bunch) and have seen lots of hooks. Not warping from the trailer, but actual desigined in hook to make the boat ride better by keeping the nose down. Hell some manufacturers are still doing it today. I even worked on an early 90's Ultra that was straight as a board for the last 6 feet, and then all the sudden is had a 3/8" hook in it on both inner lifting strakes right at the transom. That one had enough glass to allow for taking it off.

[garrett]

when the fiberglass cures in the mold it causes a mild hook at the transom. when my dad would build a race boat or when speed is a concern for a customer. he would grind the hook out after it leaves the mold. maybe some manufactures build this into there design but it does happen naturaly while it cures in the mold.

[garrett]

http://www.***boat.com/image_center/data/524/1373P1250014.jpg
picture of the miller flatbottom just after we blueprinted it.

[Marlin455]

I am about to start the hook removal process on my 18' Marlin jet hull-not too bad, but definitely measurable in spots-
My question is this- anyone out there know why the lower edge of the transom is rounded? It would seem to me that a sharp edge at the transition point from transom to keel all the way across would be better for "breaking" the water away from the hull- Any thoughts?
My other question- is there any benefit to sharpening the lifting strakes while I'm there?
BTW- This hull is a splash of the Tahiti/ Shuster/ Sidewinder hull bottom- deep entry vee. Thanks, Stan

[DUCKY]

Anywhere there is a corner, the sharper the better. Pay particular attention to the last six feet of running surface in the middle, and about a 15degree angle back up the sides. Flat and straight with nice sharp edges is the best for performance.