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86 Mirage rebuild

Posted: Sun Mar 08, 2015 12:08 am
by 1986Mirage
Hi all, I could use a bit of guidance with my boat rebuild.
The boat: 1986 20ft mirage fish/ski. Beam is about 8.5 ft. Powered by a Stern drive 230MR.
Full stringer/transom rebuild underway. Have all the old stuff out. Complete removal. No wood left in boat. Ready, almost to put in transom.
Transom original thickness was 2" for 2' around the outdrive. 2* 3/4 ply plus 1/8 outer layup and 3/8 inner layup. Rest of transom had 1/2 plywood with the same fiberglass thickness.
I am adding a kicker motor to one side as well as making a new aft platform. Thus, I'm making the whole transom 2" thick (2* 3/4 meranti plywood) and adding some stringer ties from the transom. Trying to add pictures, but I'm not able to with the tablet. I will do with the computer on Monday.
My questions for now are, do I epoxy glue the first layer of plywood to the outer fiberglass? The surface of the fiberglass is very uneven. My concern is getting enough epoxy glue on there and clamping the plywood, all before it sets up. Where I live, the temp does not allow a slow set epoxy.

My other fear is that I deflect the plywood to much, thus causing a stress on the plywood to fiberglass bond when I remove the clamps. Do you think this is a reasonable fear?
The transom is such I will have to laminate the plywood in the boat.
Any advice is much appreciated. Thank you in advance.

Re: 86 Mirage rebuild

Posted: Sun Mar 08, 2015 9:40 am
by lawtoolguy
Hello,

Sounds like you have gotten allot of the dirty work completed. I'm not an expert but I can pass on what has been shared with me while doing my transom. Once you have all the old wood ground down to outer layer of glass you'll want to get everything in place. Coat first layer of new plywood with un-thickened epoxy and set it aside. Mix up your thickened epoxy to peanut butter consistency with wood flour.Apply to your inner layer of glass with a 1/4 inch notched trowel then do the same to your 1 st layer of plywood. Once they are sandwiched together you will have a good buildup of glue. Then clamp them tight enough to allow for a little to ooze but not to tight that all the glue comes out. I used 1" x 6" boards on inside and outside threw bolted in existing holes to clamp my layers. Make sure you wrap the bolts with clear tape to make for easy removal. To fill the gaps around edges I used thickened epoxy with wood flour and milled glass. My surface was slightly uneven and had some dry spots in the old glass that filled with thickened epoxy before starting. It really helps to have everything in place and tested and also an extra person for mixing. You will Fill bolt holes that are not needed later with thickened epoxy. There is allot of good info here. I think I spent 2 days reading links before even getting my materials together

Hope this helps

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Re: 86 Mirage rebuild

Posted: Mon Mar 09, 2015 2:40 pm
by 1986Mirage
Thanks for the quick reply! Yes, that information helps alot. I had been reading the tutorials on here, but had overlooked that last little piece.

Ordered all the epoxy and what not from the website today. For some reason, I'm not able to post pictures. It is probably a setting issue on my computer or something.

in anycase, once i figure out how to post the pictures (maybe I need to resize them?) I will post how it turns out and any questions along the way I run into.

Re: 86 Mirage rebuild

Posted: Tue Mar 10, 2015 5:28 pm
by 1986Mirage
Maybe someone could help with a lamination schedule for the stringers and transom?

Transom: 2" thick total. 2*3/4" plywood. Outer skin was 1/8" thick. Inner skin was 3/8" thick.
Stringers: 1" thick total. 1 piece of 3/4 plywood with 1/8" thick on either side.

Also, how many layers of biaxial 25oz tape would you recommend on the stringers to hull and transom to hull?

Still trying to figure out the pictures

Re: 86 Mirage rebuild

Posted: Tue Mar 10, 2015 7:51 pm
by 1986Mirage
Ordered all the epoxy and what not yesterday. To my surprise, it all shipped within a couole hours.

See if this works for some pictures...they may help with the laminate schedule.
http://gallery.bateau2.com/albums/userp ... 3254~0.jpg

http://gallery.bateau2.com/albums/userp ... 943338.jpg

http://gallery.bateau2.com/albums/userp ... 332866.jpg

http://gallery.bateau2.com/albums/userp ... 613887.jpg

Re: 86 Mirage rebuild

Posted: Tue Mar 10, 2015 7:56 pm
by 1986Mirage
For those of you whom are as technically challenged as myself. To post a pic from a droid phone, you have to first resize the picture by sending it to yourself. Then go to the builder forums and upload the file, one that isn't 4.5 mb :).
You can then paste a link in the comment section.

Re: 86 Mirage rebuild

Posted: Tue Mar 10, 2015 9:27 pm
by pee wee
You almost had it- after you paste the url into your message, highlight it and hit the Img button. Do a preview of your message before you hit submit, and it should show as a photo.

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Re: 86 Mirage rebuild

Posted: Wed Mar 11, 2015 10:40 am
by tech_support
Transom: 2" thick total. 2*3/4" plywood. Outer skin was 1/8" thick. Inner skin was 3/8" thick.
That is an abnormally thick inner skin 8O

More typical of a boat that sixe is 1/8" t0 1/4" inside skin. To rebuild that thickness you will use approximately 3 layers of 1708. Perhaps they just used a ton of matt in there :doh:
Stringers: 1" thick total. 1 piece of 3/4 plywood with 1/8" thick on either side.
It would be easier for you to just use two layers of 1/2"
Also, how many layers of biaxial 25oz tape would you recommend on the stringers to hull and transom to hull?
i would use something lighter like 2 x 12 oz of maybe 1708 tape at the max. If you are wrapping the stringers with cloth (overlap to the hull) then you can use less tabbing

If it were mine, I would tab with 2 layers 12 oz biax then wrap with one layer of 1708

Re: 86 Mirage rebuild

Posted: Wed Mar 11, 2015 3:56 pm
by 1986Mirage
Thanks for replies gentlemen. It looks like someone else has opened up this boat. Maybe they added extra to the inside skin? In any case, I'll let you know how it goes, all the supplies should arrive by Monday :).

Re: 86 Mirage rebuild

Posted: Thu Mar 12, 2015 11:06 pm
by 1986Mirage
Has anyone seen an msds for the marinepoxy? In the northwest the temp is fluctuating to the point of needing to heat the shop while the marinepoxy is kicking. My heat source is a wood stove. Want to be sure I don't burn down the shop with an open flame source. Of course, I will keep it ventilated. Thanks in advance to the replies.

Re: 86 Mirage rebuild

Posted: Fri Mar 13, 2015 9:09 am
by jacquesmm
There is somewhere at boatbuildercentral.com, an MSDS for Marinepoxy but I am certain that it is not flammable.
The danger is with acetone that you probably have around the shop.
For the cure times, see this:
http://www.bateau2.com/howto/cure_times.php

Re: 86 Mirage rebuild

Posted: Fri Mar 13, 2015 9:14 am
by Cracker Larry
Epoxy is not flammable at all, but like Jacques said, watch out for acetone, alcohol, mineral spirits and lacquer thinner around the wood stove.

Re: 86 Mirage rebuild

Posted: Sat Mar 14, 2015 10:51 pm
by 1986Mirage
After doing some searches to no avail, I thought I would post and ask for your all experience on urethane covering epoxy (with one layer of 17oz with 8oz Matt on top of deck) on top of meranti 1088. I will be using the marinepoxy. Does it turn out clear enough to justify the 1088? How does it hold up to wear and tear? I was also going to add some nonskid to one of the top epoxy coats. Done my fair share of teak and other wood on decks, but never plywood. And maybe someone has a suggestion for a type of urethane over the marinepoxy?

Re: 86 Mirage rebuild

Posted: Sun Mar 15, 2015 8:14 am
by Walkers Run
I used the EMC clear coat over Marine epoxy on my mahogany toe rail with very good results. No glass on mine though.

Re: 86 Mirage rebuild

Posted: Sun Mar 15, 2015 10:26 am
by Cracker Larry
The EMC clear coat sold here seems to be excellent. We'll have to wait and see how it holds up in the long run, but it sure is purty when it goes on :D

Re: 86 Mirage rebuild

Posted: Tue Mar 31, 2015 3:09 pm
by 1986Mirage
A quick update and a couple of questions:
The transom rebuild is complete. Although i need to install all the hardware still. A couple questions on that below. I Used the maring epoxy from Bateau and it is real nice to work with. Can't say enough on the support from Bateau, including shipping speed. I cut and laminated the stringers last weekend. I was surprised at the shipping speed. I live in the opposite corner of the US (washington state) and it still arrived within a week.
Floor panels are cut to fit, obviously not installed yet :).
I will post some pics later while not on my lunch break at work.
Two quick questions:
- On a planing hull, do you recommend using a mechanical fastener on the floor as well as gluing or will gluing hold by itself? I plan on wrapping the plywood floor with glass (and epoxy obviously :)) If the mechanical fastener (i.e. screw) is needed, I imagine you drill a bigger hole, fill it with thickened epoxy, then drill the right size and install the screw. Do I have that correct?

- For through transom fasteners:
-- Should i use a brass or stainless sleeve/tube between the fastener and the thickened epoxy? I'm not sure about how brittle the thickened epoxy becomes over time. My only concern is the thickened epoxy may crack over time if there is a side load from the fastener...thus allowing water into the transom. Or maybe the sleeve is not necessary.
-- Do you recommend a type of sealant for the gimbal housing to the transom plate? There is a foam gasket, but i'm wondering if i should put some sealant around the mating surfaces as a precaution. What type of sealant would you use?



Thanks guys!

Re: 86 Mirage rebuild

Posted: Tue Mar 31, 2015 3:42 pm
by jacquesmm
1986Mirage wrote: Two quick questions:
- On a planing hull, do you recommend using a mechanical fastener on the floor as well as gluing or will gluing hold by itself? I plan on wrapping the plywood floor with glass (and epoxy obviously :)) If the mechanical fastener (i.e. screw) is needed, I imagine you drill a bigger hole, fill it with thickened epoxy, then drill the right size and install the screw. Do I have that correct?
I don't know . . . We try not to use any fasteners. Wherever there is epoxy, the bond is going to be stronger than fasteners.
If you look at this page:
http://www.bateau2.com/howto/repair.php
you'll see how we weld the sole to the framing and sides: no fasteners.

- For through transom fasteners:
-- Should i use a brass or stainless sleeve/tube between the fastener and the thickened epoxy? I'm not sure about how brittle the thickened epoxy becomes over time. My only concern is the thickened epoxy may crack over time if there is a side load from the fastener...thus allowing water into the transom. Or maybe the sleeve is not necessary.
In small boats, I never use a sleeve and trust the epoxy. Most of our builders always use a sleeve. It's your decision.


-- Do you recommend a type of sealant for the gimbal housing to the transom plate? There is a foam gasket, but i'm wondering if i should put some sealant around the mating surfaces as a precaution. What type of sealant would you use?



Thanks guys!
That last one is question for the sterndrive manufacturer and I guess that no mechanic would like to remove a gimbal sealed with 5200! Other sealants may be fine but if there is a foam gasket, it's probably sufficient. I am not certain.

Re: 86 Mirage rebuild

Posted: Tue Apr 14, 2015 12:05 am
by 1986Mirage
Haven't posted in a while, been busy working on the boat and not on the net. Below are some pictures.

Next I need to get all white the antifouling paint (or is it gel coat?) off.There is a red coat under the white, thus i'm thinking it must be an antifouling paint. Other opinions? If the white is a gel coat, i can primer right over it (after sanding). If not, and i take the risk, I will be doing the hull paint again.

One question i have for the designers...
I want to add a transom width platform (a.k.a swim platform). I also want to mount a kicker on the aft/starboard side of the platform. The kicker weighs 108lbs. It would hang 1.5' off the the transom. Any idea if the step will hold the kicker? Obviously i plan on putting angle braces (4 of them) under the platform. Is this a bad idea? The other option is to put a removable portion of the platform and mount the kicker right on the transom.

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Re: 86 Mirage rebuild

Posted: Tue Apr 14, 2015 10:02 am
by jacquesmm
1986Mirage wrote: Next I need to get all white the antifouling paint (or is it gel coat?) off.There is a red coat under the white, thus i'm thinking it must be an antifouling paint. Other opinions? If the white is a gel coat, i can primer right over it (after sanding). If not, and i take the risk, I will be doing the hull paint again.
You'll see what it is while you grind it off. Once you get to the polyester (gel coat is polyester), grind the smoothness down for the paint to get a good grip and that is the surface you start working on.

Primer then paint of your choice.
The System Three primer is great, it is an epoxy and works will any paint.
If you are going to paint with bottom paint later, stop at the primer. Put a couple of coats on and that's all you need.

Re: 86 Mirage rebuild

Posted: Tue Apr 14, 2015 10:08 am
by jacquesmm
1986Mirage wrote: One question i have for the designers...
I want to add a transom width platform (a.k.a swim platform). I also want to mount a kicker on the aft/starboard side of the platform. The kicker weighs 108lbs. It would hang 1.5' off the the transom. Any idea if the step will hold the kicker? Obviously i plan on putting angle braces (4 of them) under the platform. Is this a bad idea? The other option is to put a removable portion of the platform and mount the kicker right on the transom.
Kicker: if you put it on the platform, the platform has to be very strong.
I would make the platform from at least 1/2" ply, double where the kicker goes and 4 vertical braces to support the platform, all tabbed with biaxial glass to the transom and to each other.

It's a lot of work but it will look good and strong.
Copy the design of an Armstrong bracket for shape and dimensions.

A kicker on a ladder will not last but you may prefer a sailboat type outboard bracket, the kind that goes up and do, next to a ladder or smaller swim platform.

Re: 86 Mirage rebuild

Posted: Tue Apr 14, 2015 10:11 am
by jacquesmm
Your fiberglass laminations are clean but do you have enough layers there? It looks thin from here.

Re: 86 Mirage rebuild

Posted: Tue Apr 14, 2015 8:04 pm
by 1986Mirage
Will do on the primer!

Hmmm, need to think about the kicker more. I'll check out the Armstrong bracket. The swing down bracket is a good idea also.

I put 3 layers of biaxial 17oz. The material had a mat, about 8oz, which was pretty heavy, but what I could get locally.
The thickness is 3/16" for the inner skin. Total transom thickness is 2". Should I put more layers on?

Thanks!!

Re: 86 Mirage rebuild

Posted: Tue Apr 14, 2015 8:10 pm
by 1986Mirage
Also, stringers have one layer of same 170z and tabbed with 4" tape.

Think that's enough? The stronger thickness is 2 * 1/2"ply whole thickness is 1."

Re: 86 Mirage rebuild

Posted: Tue Apr 14, 2015 8:28 pm
by 1986Mirage
....and the stringers are 2* 1/2" ply laminated together, then tabbed with 4" biaxial tape (1708) and wrapped with one layer biaxial 25oz. Do you think that is sufficient? I was thinking it was overkill, but it's what I could get.

Re: 86 Mirage rebuild

Posted: Wed Apr 15, 2015 11:09 am
by jacquesmm
1986Mirage wrote:....and the stringers are 2* 1/2" ply laminated together, then tabbed with 4" biaxial tape (1708) and wrapped with one layer biaxial 25oz. Do you think that is sufficient? I was thinking it was overkill, but it's what I could get.
The tabbing is not insufficient.
In a previous post, we said 2 layers of 12 oz. plus one layer 1708.
The previous tech support guy was not a yacht designer and I find his specs a little light but it can work if done as tabbing, not just wrapping the stringers in glass.
That means, all those layers go from the stringers to the hull, not just cover the stringers.

You need a minimum total of about 50 oz. between stringers and hull. It looks like you have about half that. I would add one more layer of 1708 or 2 layers of 12 oz.
Please use wider tape: 4" wide is too narrow.
That stringers tabbing is the backbone of your boat, don;t be shy with the fiberglass.

Re: 86 Mirage rebuild

Posted: Wed Apr 15, 2015 9:47 pm
by 1986Mirage
50oz minimum aye. I have some 8" -12 oz biax tape with 6 oz mat, that will push me over 50oz.

Is it a problem that I've wrapped the stringers already? I imagine I can lay 8" tape over the wrap. However, I overlayed the wrap by more than 4 " to the hull. So the 8" tape would just be on top of the wrap. What would you do in this case?

Thanks for the help!

Re: 86 Mirage rebuild

Posted: Thu Apr 16, 2015 10:43 am
by jacquesmm
It is not a problem to have the stringers wrapped in glass but we need that strong angle, the tabbing.

Re: 86 Mirage rebuild

Posted: Sun Apr 19, 2015 11:42 pm
by 1986Mirage
On the Armstrong bracket for a kicker...looks like a good idea, I'm going to build one, my wallet won't handle buying one. I've done quite a bit of research and have not found a good dimension. Your input would be of great help.

Here's what I'm thinking, transom width step with kicker on stern of step offset to the starboard side.
Kicker 122lbs, 9.9 horse.
More significant is the force from people on the step. I'd say designing it to hold two men would be ideal. I.e., 400lbs.
Transom is 2-3/4" ply glued together. Tabbed with 3layers. 4", 6", then 8". Then 3 layers of 25oz over that. To equal 2" thick total. Thicker at tabbed edges.
Step dimensions are approx. 24" * 80"
Made of 1/2marine plywood. With 15/16" total thickness under kicker motor.
On either side of stern drive there will be 2* support brackets. Total of 4 support brackets across transom under swim step.
Space the support brackets 12" apart equally centered on either side of stern drive.
The starboard supports will be directly under the kicker motor.
The port side will be directly under the swim ladder.

My questions are,
I could box in the support brackets. Is this necessary? Or can I leave the space between the supports open?
If boxing, do you suggest or sell an access port?
The support bracket dimensions would be3/4" plywood. 24" along the top and 12" along the back. With a 22.5° angle making the triangle. Is this too sharp of an angle? Or could make the shape like a half of a trapezoid if necessary.

My fear of boxing the supports in is the force it puts on the transom before on plane. Maybe this is negligible?

What laminate schedule would you use for tabbing the supports to hull?
I was planning on sealing the step and supports with glass. I have a whole half role of biaxial 8oz, no mat left over from another non marine project..itis epoxy compatible...Would 1layer of that suffice?

Ordering the paint up this week and should get to the gimbal and outdrive installation this weekend :D

Re: 86 Mirage rebuild

Posted: Mon Apr 20, 2015 9:50 am
by jacquesmm
I was asked many times and always refused to design a bracket.
While working in production boats, I have seen many professionally built brackets fail. The brackets themselves fail or the bolts or the transom.
Find a good used bracket, it will be safer.