1992 Marada 1800MVB.. stringer, transom, deck restore

[Woodonglass]

Re: 1992 Marada 1800MVB.. stringer, transom, deck restore

If you have any Scrap CSM and a pair of scissors, you can make your own. YOu only need about 1/4 of a cup per quart of resin. Aerosil and resin will work but adding the fibers sure makes it stronger.

 

[Marada92]

Re: 1992 Marada 1800MVB.. stringer, transom, deck restore

Hmmm didn't even think about that... Thanks wood!

 

[Marada92]

Re: 1992 Marada 1800MVB.. stringer, transom, deck restore

Fuel tank floor... Still needs some csm on top.

Supports for engine stepouts... They are in need of some sanding... I got messy on it since it was 98 today and resin was kicking off faaaasssst.

New material I'm trying in place of wood... 1/8" cardboard! Figure with about 30 layers of 1708 it should be just as strong as wood!!! Right?!!

But seriously.. Those little templates made getting the 3/4 ply cut easily! Busy till Monday so hopefully next week I can get everything covered in csm and the support tabbed in with 1708. Test fit the boards I just cut and gets those glassed in. Will be ready to gel coat everything that has to be done before I can start laying deck! FINALLY!

 

[jbcurt00]

Re: 1992 Marada 1800MVB.. stringer, transom, deck restore

Cardboard really drinks the resin, be careful not to compromise the fore aft weight distribution

Templates good

Climbing in & out of the deck-less boat 18 times to trim 2 small 3/4" pcs of ply, yeah, not so much

all that work looks good, 98+ heat or not....

 

[Pmccraney]

Re: 1992 Marada 1800MVB.. stringer, transom, deck restore

Nice work...

 

[Marada92]

Re: 1992 Marada 1800MVB.. stringer, transom, deck restore

Cardboard really drinks the resin, be careful not to compromise the fore aft weight distribution

That's what a fat friend in the front of the boat is for! Cheap ballast I say.... Just keep a variety of people aboard of different weights to instantly change your wake characteristic!

 

[Marada92]

Re: 1992 Marada 1800MVB.. stringer, transom, deck restore

Got some free time today to get some work done... I must say knowing that I'm getting closer and closer to being done is making want to work on this thing more and more!
Here's the ski locker mocked up with CSM.

Ski locker and fuel tank floor covered with two layers of CSM!

Engine mount supports tabbed in.

Test fitting the stepouts.

Hope to get the underside of these covered in csm tomorrow so they can be glued in Tuesday. Also planning on capping the back stringers tomorrow.
Have one question... Would it be worth it to fill the open area below the engine mounts with foam? Only wondering because I'd have to hold off on putting the 1708 over all this until I get foam.

 

[Marada92]

Re: 1992 Marada 1800MVB.. stringer, transom, deck restore

No one have any advice on that?

 

[jbcurt00]

Re: 1992 Marada 1800MVB.. stringer, transom, deck restore

I was under the impression that the IO motor mount 'stringers' were supposed to be substantial. As in filled solid w/ plywood wrapped w/ glass & PB'd to the hull, if lagged down. Or at least so the lag screw runs thru & bites into more then just 1 thickness of 3/4" ply.

Multiple layers of 3/4" ply wrapped w/ glass, then PB, tabbing & glassed to the hull, if thru bolted.

How do your motor mounts attach to these pcs of plywood?

Questions more then answers, sorry to not be of more assistance....

The rest of the tabbing & glass work looks good

 

[Struc]

Re: 1992 Marada 1800MVB.. stringer, transom, deck restore

I went back and looked at page 1 & 2 where you had pictures of the original motor mounts and were discussing this design.

I have to agree with some of the people back there that said this doesn't look as strong as the old design. I would, at a minimum, double up the inside stringer on each side and the top piece. You really want to beef that area up. You have an awful lot of weight sitting there vibrating. You want it as solid as possible.

I personally would have rebuilt it with solid wood, or close to it.

What are you going to make the actual motor mount block out of that sits on top of that step?

 

[Marada92]

Re: 1992 Marada 1800MVB.. stringer, transom, deck restore

The old design was nothing but three 2x4 nailed to eachother and nailed to the stringers... Only one corner of those 2x4's even rested on the hull. The other two were just floating an inch above the hull. There wasn't even a horizontal plywood piece laid across the top they just went crazy with the chopper gun and built up half an inch of glass over the top of all it... Stuck a 4x4 block on top of that to mount the motor to and covered it the same way.
They way it's done now is the two stringers were glued in with Pb and tabbed followed by a 1.5" support pb'd to the outer stringer and also tabbed in with 1708. Already glued in the horizontal step that the motor mount block rests on so there's no adding to it now. Without any glass on it the thing is solid now. I plan to run multiple 1708 layers over this entire structure and to the hull. If you recall on Frisco's thread the motor mounts blocks that held that 454 are simply 1.5" of plywood glued to the hull and tabbed to the inside stringer to form a 3 sided box. If something that simple will hold that engine this should do fine also. But now as far as the block that the motor mounts attach to I am leaning towards stacked plywood and then lag bolts. Everyone had said the idea about the 2" cleat attached to the stringer alone wasn't enough which I now agree with... Don't know what I was thinking. But everyone at that time agreed that as long as you had all the downward force being transferred to the hull all should be well which is what I have now. Thank you for the advice fella's unfortunately I was unable to read it until after I was past the point of no turning back, but I believe I will be ok here... I hope! Lol

 

[jbcurt00]

Re: 1992 Marada 1800MVB.. stringer, transom, deck restore

That reads like it was well thought out, and better then original. The pcs you were asking about & put down today, are not the primary connection between the boat & the motor mount. These 'shelves' support the plywood built up block(s) that the motor mounts attach (lag) to.

Well done

It looked like these shelves would have a mount lagged to the top of them directly, which didn't look/sound substantial enough:redface:

 

[Marada92]

Re: 1992 Marada 1800MVB.. stringer, transom, deck restore

That reads like it was well thought out, and better then original. The pcs you were asking about & put down today, are not the primary connection between the boat & the motor mount. These 'shelves' support the plywood built up block(s) that the motor mounts attach (lag) to.

Well done

It looked like these shelves would have a mount lagged to the top of them directly, which didn't look/sound substantial enough:redface:

Sorry for the confusion... Yes those shelves are there mostly just to form the step though they are what the other block rests on. I'm going to try and draw up the actual design I have now just to clear up any confusion I may have added.
Back to my question this stemmed from... About foaming the cavity. I was only wondering if doing this would just add a bit of extra stability to the whole structure more so than just having an open void there. Thank you again for yalls concern and advice. Havent had a ton of people following this thread to lend advice so I've been going off what I've learned from others projects... Mostly Frisco's.

 

[Struc]

Re: 1992 Marada 1800MVB.. stringer, transom, deck restore

My concerns mainly stem from vibration, not how strong it is. Having the engine mount block sit on that shelf, I have no doubt it will handle the weight without any issue. My concern is when that weight is vibrating. I'm guessing the old blocks of wood were in there, not for any kind of weight holding ability (since they didn't touch the hull), but to absorb and transmit the vibration evenly over a wider area. I could certainly be wrong. I am by no means an engineer. I guess I'd just be concerned with the wood cracking over time. I hope I'm wrong.

 

[jbcurt00]

Re: 1992 Marada 1800MVB.. stringer, transom, deck restore

In that location, I wouldn't really be too concerned about the evils posted about using pour in foam, if you just want it to be filled. The foam won't really do that much for you as flotation or 'bulking up' the cavity. That's of course based on you using pourable foam elsewhere. Not spray can'd foam


Sealed those compartments might add the slightest, marginal measure of flotation by having air sealed inside of them anyway. The pink & blue insulation sheets that are frequently discussed, also wouldn't add much in that small a space. If you are leaning that way re: flotation foam....

Help?

 

[jbcurt00]

Re: 1992 Marada 1800MVB.. stringer, transom, deck restore

My concerns mainly stem from vibration, not how strong it is. Having the engine mount block sit on that shelf, I have no doubt it will handle the weight without any issue. My concern is when that weight is vibrating. I'm guessing the old blocks of wood were in there, not for any kind of weight holding ability (since they didn't touch the hull), but to absorb and transmit the vibration evenly over a wider area. I could certainly be wrong. I am by no means an engineer. I guess I'd just be concerned with the wood cracking over time. I hope I'm wrong.

Carp, wish I'd seen this before the above

Unless you fill the open cavity with material that would vibrate & transmit vibration at the same rate as the 'box' we're talking about, I'm not sure how foam filled will help in the transmission of vibration all that much. But like you say, I too am not an engineer. Foam might dampen the vibration, though. Which may help the long term impact of vibration cycling the 'boxes' to hull & motor connections.

 

[Marada92]

Re: 1992 Marada 1800MVB.. stringer, transom, deck restore

Glued and filleted... Glassing to begin tomorrow.

 

[jbcurt00]

Re: 1992 Marada 1800MVB.. stringer, transom, deck restore

Great!

 

[Marada92]

Re: 1992 Marada 1800MVB.. stringer, transom, deck restore

My concerns mainly stem from vibration, not how strong it is. Having the engine mount block sit on that shelf, I have no doubt it will handle the weight without any issue. My concern is when that weight is vibrating. I'm guessing the old blocks of wood were in there, not for any kind of weight holding ability (since they didn't touch the hull), but to absorb and transmit the vibration evenly over a wider area. I could certainly be wrong. I am by no means an engineer. I guess I'd just be concerned with the wood cracking over time. I hope I'm wrong.

I can see what you are saying now. Though as completely rotten as all this was it was basically just being held together by the fiberglass and it still had yet to crack anywhere. So im hoping I will still be good. Looking back I remember thinking about adding another stringer basically making that inner most stringer a 1 1/2 piece but decided against it... laziness probably. Thanks again though.

And also JB I am planning on using 2lb pour foam under the entire deck.

 

[jbcurt00]

Re: 1992 Marada 1800MVB.. stringer, transom, deck restore

Flotation is for each to choose. Any is better then none And done well, & well maintained pour in is certainly the standard others are compared to.... If I never read another debate for & against any of the 'choices' it will be way too soon