SoCal Jet Boats

Tech Talk => Projects => Topic started by: theskitzofrantic on September 22, 2008, 04:30:20 PM

Title: 1984 MANTRA project
Post by: theskitzofrantic on September 22, 2008, 04:30:20 PM
So far only real problem besides not having an engine is I found a  rotten broken stringer that had been patched, not good either so I am in the process of trying to fix that....any ideas would be a big help.


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Title: Re: 1984 MANTRA project
Post by: FORKEDUP on September 22, 2008, 04:39:58 PM
cool boat, i really think it is going to be to much work for you and you should just send it my way >:D
Title: Re: 1984 MANTRA project
Post by: TJS Nordic on September 22, 2008, 06:12:15 PM
welcome to the site. Nice Gel on that thing. Cut both stringers out and replace both. Do a search on PB and here. I know someone has documented it somewhere. Your boat is all there just got to get it to the detail where you want it.
T.J.
Title: Re: 1984 MANTRA project
Post by: beerjet on September 22, 2008, 08:31:15 PM
Try and get them out complete so you can reproduce them making for a better fit .
Nice gullwing , didnt know Mantra made one though . Sexy either way .

-beerjet-
Title: Re: 1984 MANTRA project
Post by: GT Jets on September 22, 2008, 09:54:48 PM
Gonna throw this at you, I will probably be proven wrong, but try to leave a small amount of the origional glass at the bottom of the stringer vertically (like an inch or so) but feather it out smoothly, it will give you a lot of added strength when the new beams are installed, otherwise you are relying on the bond of the new glass to old, also may look into epoxy resins, West Systems is really cool stuff and does not have some of the issues of the polyester resins, just a recomendation though, I love the stuff.

Good luck, cool little project and welcome aboard...

GT
Title: Re: 1984 MANTRA project
Post by: theskitzofrantic on September 22, 2008, 11:42:19 PM
any way that I can save part of old stringer and tie into it?
Title: Re: 1984 MANTRA project
Post by: beerjet on September 23, 2008, 12:07:39 AM
any way that I can save part of old stringer and tie into it?
Nope . Make sure all the wood comes out . GT's idea sounds good too .

-beerjet-
Title: Re: 1984 MANTRA project
Post by: GT Jets on September 23, 2008, 12:36:11 AM
Nope . Make sure all the wood comes out . GT's idea sounds good too .

-beerjet-

X2 Any old wood could rot and you're back to square one, besides one piece is always stronger...It should come out easy, probably easier than you think.

GT
Title: Re: 1984 MANTRA project
Post by: theskitzofrantic on September 23, 2008, 07:00:55 AM
Would there be any problem using alum. channel instead of wood?
Title: Re: 1984 MANTRA project
Post by: GT Jets on September 23, 2008, 08:01:42 AM
Would there be any problem using alum. channel instead of wood?

The only issues that I can see is that fiberglass resins, including epoxy, will not adhere to the aluminum, way too many issues with oxidation and the aluminum has very volitile expansion and contraction issues

Thinking outside the box though ;)

GT
Title: Re: 1984 MANTRA project
Post by: theskitzofrantic on September 24, 2008, 05:05:50 AM
I am almost ready to start the removal of the stringers but haven't been able to find any real instructions on how to go about doing it. It only has two and they run way up into the bow of the boat seems like maybe just replacing them up to say... the dash would be enough but I am new to this whole scene and am looking for some guidence.
Title: Re: 1984 MANTRA project
Post by: theskitzofrantic on September 24, 2008, 06:01:58 PM
Got driverside stringer and subfloor out today....what a mess!!

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(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fi86.photobucket.com%2Falbums%2Fk93%2Ftheskitzofrantic%2F100_1755.jpg&hash=5f650dc36ec346faedc11b318843cb694c990d05)

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Title: Re: 1984 MANTRA project
Post by: Ralph Brunt on September 24, 2008, 06:19:18 PM
i cant tell if you are doing this on the trailer or not, when you  put the new stringers in the boat needs to be off the trailer and on 3 points. 2 at the rear and one at the front so the boats bottom is relaxed and not taking on the shape of the trailer bunks. just what i was told when kenny at bk boat repair did my stringers. i'll see if i have any pics of it.
Title: Re: 1984 MANTRA project
Post by: Ralph Brunt on September 24, 2008, 06:26:09 PM
sorry dont have any pics of the way he had it set up
Title: Re: 1984 MANTRA project
Post by: enginedoctor on September 24, 2008, 07:34:15 PM
Not to change the subject....but  Last time  I was at the river  I saw something  I have never seen before ???

A  boat with tandem  JETS............   /   Two  Engines  side by side.... Absolutely  awesome!

Anyone  see that before  ??? ??? ??? ???
Title: Re: 1984 MANTRA project
Post by: GT Jets on September 24, 2008, 09:57:37 PM
There is a video of a guy with a twin jet on youtube, I'll scare it up and post it in the no wake zone..

BTW theskitzofrantic, looks good, and X2 the getting the boat bottom freed up, the way I was taught is to block up the left and right rear corner on the trailer and block the veed section on the first trailer crossmember, works like a champ IMO.

GT
Title: Re: 1984 MANTRA project
Post by: theskitzofrantic on September 25, 2008, 05:22:59 AM
I am having a heck of a time trying to find any one that can get me Douglas Fir boards.....anyone have any ideas?
Title: Re: 1984 MANTRA project
Post by: Ralph Brunt on September 25, 2008, 06:50:07 AM
I am having a heck of a time trying to find any one that can get me Douglas Fir boards.....anyone have any ideas?
make sure the wood is kiln dried
Title: Re: 1984 MANTRA project
Post by: GT Jets on September 25, 2008, 06:14:29 PM
I am having a heck of a time trying to find any one that can get me Douglas Fir boards.....anyone have any ideas?

I don't know of any one who could get it in Indiana, if its available maybe try Ash? I've never used it but I'm not sure, it would be plenty strong and might be cheaper in your area...Just a suggestion.

GT
Title: Re: 1984 MANTRA project
Post by: nathan72 on September 25, 2008, 07:21:57 PM
is there a part# on that blue ignition switch i need to get one ???
Title: Re: 1984 MANTRA project
Post by: theskitzofrantic on September 27, 2008, 04:40:07 AM
Anybody have a link to the  step by step instructions to finish this project. :banghead:
Title: Re: 1984 MANTRA project
Post by: OC2Vegas on September 27, 2008, 11:31:30 AM
Anybody have a link to the  step by step instructions to finish this project. :banghead:

For the instruction:

www.socaljetboats.com (http://www.socaljetboats.com)

and for the parts you'll need:

www.jetboatperformance.com (http://www.jetboatperformance.com)
Title: Re: 1984 MANTRA project
Post by: theskitzofrantic on October 01, 2008, 07:05:17 AM
Would a regular old pressure treated 2X6 work for the stringers? I am having no luck getting ahold of any fir or ash boards.
Title: Re: 1984 MANTRA project
Post by: The Chaz on October 01, 2008, 07:50:31 AM
You want a board that can soak up a few coats of resin.  I think the pressure treated stuff is poor at this.  Also check that 2x4 is wide enough. I needed 2x6 when I did my floor "stringer" due to the curve of the bottom  of the boat.  I am not a wood expert but I think a good grade board with a lot of resin in it would be fine.  I think the fewer knots in the wood the better also.
Title: Re: 1984 MANTRA project
Post by: TJS Nordic on October 01, 2008, 08:12:59 AM
Don't use pressure treated wood. That shit will warp like an aircraft propeller when it dries out.
T.J.
Title: Re: 1984 MANTRA project
Post by: GT Jets on October 01, 2008, 08:49:10 AM
Don't use pressure treated wood. That shit will warp like an aircraft propeller when it dries out.
T.J.

ROFLMAO!

You really can't find anyone that carries fir lumber? What do you guys build your homes out of, Balsa?

Do you have a cabinet shop in your area, they may be able to point you to a supplier that can handle this, they deal with kiln dried lumber on a daily basis, just a thought...

I can go buy as much Fir as I can afford just 12 miles away, I'm very suprized...

Do not use wood with any treatment other than dried, the resin will fight it off like a Raider coach  :o

  ;D GT
Title: Re: 1984 MANTRA project
Post by: realHawaiianJet on October 01, 2008, 09:32:27 PM
Here ya go skitzo, this is probably one of the best threads that I've ever seen on replacing stringers, the right way. ;) and it has nice large very detailed pictures!!!! ;D

And please, for the sake of your boat, DO NOT REPLACE THE STRINGERS ON THE TRAILER, or your hull will end up like mine, jacked all to hell, and riding very wet and slow!!!!!!! :banghead: I wish I would have known about these sites before replacing a section of my center stringer, now I can't even find a flat spot on the bottom of my boat, and it is twisted, but I also have a jacked up trailer that is causing part of my problem. :banghead:

If you do it on the trailer, you are removing all rigidity from the hull, and the trailer bunks will push the bottom in, and when you put the new stringers in, you will be permanently setting that form into the bottom of the hull. And that will seriously fuck things up!!! ;) Take your time and do it right, or don't do it at all. ;)

http://www.performanceboats.com/html/forums/showthread.php?t=4604&highlight=Stringers (http://www.performanceboats.com/html/forums/showthread.php?t=4604&highlight=Stringers)\

Good luck. :)
Title: Re: 1984 MANTRA project
Post by: theskitzofrantic on February 02, 2009, 01:32:33 PM
Still unable to find FIR lumber in the state of Indiana, don't know what to do....anyone have any ideas?
Title: Re: 1984 MANTRA project
Post by: 76 Bonneville on February 02, 2009, 02:23:12 PM
Mahogany, probably a little spendy.
Title: Re: 1984 MANTRA project
Post by: Stevecat on February 02, 2009, 03:04:52 PM
Still unable to find FIR lumber in the state of Indiana, don't know what to do....anyone have any ideas?

http://www.bearhollowindiana.com/kilndrylumber.html
ash will work. poplar too. maybe the hickory.

http://www.benderlumber.com/our_products.htm
I think the stuff they list under premium grade lumber/standard lumber will work.

And there's always Home Depot/Lowes. They usually have both kiln dried and construction grade. Just tear through the entire pile and hand pick the best boards you can find... I'm usually the next guy after you trying to figure out wtf happened to the pile!!!

Good luck!
Title: Re: 1984 MANTRA project
Post by: Oldsquirt on February 02, 2009, 06:40:06 PM
Still unable to find FIR lumber in the state of Indiana, don't know what to do....anyone have any ideas?

Call Duane at Hi-Tech Performance (http://www.hi-techperformance.com). He is located next door in Missouri, and does business with several boat builders. He should be able to point you in the right direction. He is also a good source for boat/pump parts and info.
Title: Re: 1984 MANTRA project
Post by: theskitzofrantic on March 14, 2009, 03:12:41 PM
Now looking for an engine for this project, what do I need to look for? I can get 454's out of trucks and RV's all day for around $500....will one of these work?
Title: Re: 1984 MANTRA project
Post by: The Chaz on March 14, 2009, 09:22:04 PM
They would be fine for a starting point.  You should rebuild it to marine specs if you want it to last.  However, a used running motor MIGHT last a while if you take it easy on the RPM's; without being rebuilt.  It's a gamble and breaking down on the water is never fun.
Title: Re: 1984 MANTRA project
Post by: theskitzofrantic on March 15, 2009, 02:58:49 AM
Marine specs?? ???
Title: Re: 1984 MANTRA project
Post by: Luckie Stiff on March 15, 2009, 08:13:01 AM
Marine specs?? ???

When an engine is built for a jet boat the piston to cylinder wall clearances are set higher than in a street engine, this is due to the fact that unlike a car engine, your pistons are going to get warmer than your block, that's why the extra clearance is needed.  That being said, a used engine normally has enough clearance in them simply from miles on the road.  I'd say you're fine with a BBC for $500 to get you on the water.  I had a boat that I put a junkyard 429 in, it ran great when I had it, still runs great with the new owner.
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