Original transom does not meet flush with hull.what to do with new transom template..

derek23

Cadet
Joined
Aug 1, 2011
Messages
10
I am replacing the transom on my 1977 starcraft stinger and upon teardown i noticed the transom ends dont meet flush at the port and starboard hull walls. questions...why did starcraft engineers do this,there must be a reason? and should I cut my new marine plywood to meet flush with the walls or cut them according to starcraft specs?
it seems like fitting them snuggly to the hull would seem stronger but I'm no physics guy either. hopefully you can see the gap in my pics,i got two finger widths at the top of transom and smaller near bottom. thanks guys!
 

Attachments

  • DSCN5154.jpg
    DSCN5154.jpg
    149.4 KB · Views: 7
  • DSCN5153.jpg
    DSCN5153.jpg
    145.2 KB · Views: 8

Woodonglass

Supreme Mariner
Joined
Dec 29, 2009
Messages
25,924
Re: Original transom does not meet flush with hull.what to do with new transom templa

R U 100% SURE that the Transom has NOT been Replaced before? It is a 34 year old boat! I'd bet a Nickel to a hole in a donut that is NOT the original transom. I'd use a compass and make my template as CLOSE to the sides and bottom of the hull as I could get them. I'm pretty sure THAT'S how it came from the Factory.;)
 

Cadwelder

Lieutenant Commander
Joined
Aug 30, 2010
Messages
1,780
Re: Original transom does not meet flush with hull.what to do with new transom templa

Nothing odd about the transom fitting loosely to the sides of the hull. The fiberglass fills the rest. I've seen bass boat trasoms (the plywood part) as much as an inch gap on both sides.

I've replaced transom cross braces (mounts horizontally) as much as 2" gap on each side.

Now as to why did the engineer design it that way? Well chances are good he didn't, but he doesn't work in the production area of the plant....if you know what I mean.

CW
 

derek23

Cadet
Joined
Aug 1, 2011
Messages
10
Re: Original transom does not meet flush with hull.what to do with new transom templa

thanks guys. I realize that a lot of boats are going to have a gap just because the hull wall is curved and the plywood edge is squared. looks like I'll get it as close as I can and fill it(epoxy putty),round it,then tab it accordingly.
 

Friscoboater

Captain
Joined
Jul 3, 2009
Messages
3,095
Re: Original transom does not meet flush with hull.what to do with new transom templa

Mine has a gap. I just filled it with a Mixture of Resin, cabosil, fiber mix.
 

ingalp01

Petty Officer 1st Class
Joined
Sep 11, 2010
Messages
357
Re: Original transom does not meet flush with hull.what to do with new transom templa

Yep, based on what I've learned, Peanut Butter to fillet the edges in and it will take up any small gaps you may have. Just get as close as you can and fill in the rest...
 

Yacht Dr.

Vice Admiral
Joined
Feb 26, 2005
Messages
5,581
Re: Original transom does not meet flush with hull.what to do with new transom templa

I am replacing the transom on my 1977 starcraft stinger and upon teardown i noticed the transom ends dont meet flush at the port and starboard hull walls. questions...why did starcraft engineers do this,there must be a reason? and should I cut my new marine plywood to meet flush with the walls or cut them according to starcraft specs?
it seems like fitting them snuggly to the hull would seem stronger but I'm no physics guy either. hopefully you can see the gap in my pics,i got two finger widths at the top of transom and smaller near bottom. thanks guys!


So are you suggesting ( from your pics ) that the OEM build of the Transom was NOT TABBED to the hull ? ..

Unless Im getting the pictures wrong here it looks like the trans was just Glued in and Not Fiberglassed tabbed.

Help me out here :) .

YD.
 

Friscoboater

Captain
Joined
Jul 3, 2009
Messages
3,095
Re: Original transom does not meet flush with hull.what to do with new transom templa

So are you suggesting ( from your pics ) that the OEM build of the Transom was NOT TABBED to the hull ? ..

Unless Im getting the pictures wrong here it looks like the trans was just Glued in and Not Fiberglassed tabbed.

Help me out here :) .



YD.

Mine wasn't
 

derek23

Cadet
Joined
Aug 1, 2011
Messages
10
Re: Original transom does not meet flush with hull.what to do with new transom templa

Yes it was glassed in,but its hard to see from pic considering i removed most of it,you can see the cut edges of the glass under my fingers,maybe 2 layers of glass. starcraft didnt spend time then to putty and filet the gap so the glass was wrapped at a 90 degree,hence most of the transom failure/leaking and so a big gap was left where puttying/filling should have been.
 

Woodonglass

Supreme Mariner
Joined
Dec 29, 2009
Messages
25,924
Re: Original transom does not meet flush with hull.what to do with new transom templa

Here's a pic of how you should do your transom...

(Click the Pic to Enlarge)


TransomBuild.jpg
 

Yacht Dr.

Vice Admiral
Joined
Feb 26, 2005
Messages
5,581
Re: Original transom does not meet flush with hull.what to do with new transom templa

I do see some glass under your fingers..but what Im asking is it looks like there is some kind of spray foam on the sides of the hull and possibly the hull itself. .. so where is the tabbing ? under the foam ? how are you going to tab this in over that black looking foam looking stuff ?

Just wondering because from your pics I see no place for you to tab your trans to at the moment.

YD.

PS. Wood..can you please change the font color yellow to something else .. I cant read what is says in the discription :) .. thanx.
 

Woodonglass

Supreme Mariner
Joined
Dec 29, 2009
Messages
25,924
Re: Original transom does not meet flush with hull.what to do with new transom templa

YD, Your wish is my command!!!;) It's GREEN Now!!!
 

Yacht Dr.

Vice Admiral
Joined
Feb 26, 2005
Messages
5,581
Re: Original transom does not meet flush with hull.what to do with new transom templa

Saweeet .. Thanks and well done as usual :) .

YD.
 

derek23

Cadet
Joined
Aug 1, 2011
Messages
10
Re: Original transom does not meet flush with hull.what to do with new transom templa

the black sprayed on foam is so old it flakes right off,I believe all it was used for was sound deadening/vibration. You can see in the new pic as I progress with tear down that the original glass was just overlapped onto the side hull walls,I wouldn't consider that tabbing where you would typically tab in at least 4 inches.Here,it only overlaps a few inches,if that,and absolutely no filler.
After researching many forums etc...the easiest and most cost effective way for me to do this,and I've combined other ideas as well is to do the following,and I'm leaving out some minor details;
1 cut my transom after making template and mark the starboard and port sides accordingly.
2 drill out the water outlet hole and the 4 motor mount holes.
3 cut 2x4s to adequate length that will cross the motor mount holes/water outlet hole for sandwiching/glueing the transom wood together before i set it,making sure to drill the bolt holes in the 2x4s through the TALL side ensuring better lateral support. use 1/2" all thread will work fine with some nuts and washers.
4 I am using polyurethane glue instead of mat or resin putty mix to bond the 3/4" marine plywood together.easier,cleaner,cheaper.once the motor bolts are in its not going anywhere.
5 polyurethane the transom plys together using notched spreader.clamp it using my pre cut and test fitted bolts and 2x4s.let it cure overnight.
6 Encapsulate/waterproof the transom using 1.5 oz chop strand mat.start with one side overlapping egde to meet with other sides leading edge,let it cure to tack free,flip it and repeat so you end up with 2 coats on the edge. let it harden overnight.
6 mix good amount of poly resin/cabosil/chop strand fiber to peanut butter consistency and apply liberally to face of hull skin.moving quickly apply the same mix to the rear face of the transom and affix to hull skin.
7 Clamp securely with your pre cut and test fitted 2x4s/bolts. The part I like about this is the clamping pressure will squeeze out putty into your filet areas giving you an adequate head start on filling.
8 moving fast still i will now fill that transom gap(which i have painstakingly reduced) with the current mix,or a if that is setting too fast i will have my son mix me a new batch of putty to fill with before i complete my putty filling and radiusing stage.
9 I will us a simple spoon to radius the putty to hull walls.
10 I plan on using 1708 biaxial to tab initially,not sure how many layers,probably 2.
11 I will now glass the whole face of the transom 3 times using the 1708 cut to 4" tab overlap for the first layer.Cut to 8"overlap for the second.Then cut to 12"overlap for the third layer.After each layer is tack free I will sand/feather into hull wall,this will promote better adhesion and strength for the next coat and look smoother.
My biggest indecision is whether to use epoxy resin or poly resin on the 1708 glass.I know you can use epoxy resin over the poly resined transom, but the epoxy is much more expensive and requires more work wetting it,which i dont mind,i'm already in it. Also,going over everything with epoxy resined 1708 will hold up better considering this is the top coat that sees all the abuse,weather,sun etc...poly resin doesnt hold up like the epoxy so why not have that peace of mind is what i'm thinking. but the cost factor is getting higher...I dunno.
I did go with standard marine grade 3/4"(cost me78 bucks sheet at local lumber yard,they get it from georgia pacific at no delivery charge to them or me)after reading gobs of pros and cons between standard marine grade/BS 1088/AB exterior/pressure treated/CDX etc...keeping in mind I have a relatively small boat,19' with a big/heavy 175 horse johnson. I weighed all the possible cons of the lesser grade plywoods including;lesser plys,more knots,voids,valleys,warps/trueness issues,scrap pieces added,etc...and the fact that the attention to detail and how they are assembled is typically less. Considering all the work that I am putting into this,I want to reduce failure and risk now and looking at the longevity piece too. For me,investing a little more to ensure a more solid and safer transom build for myself and my children is worth it.
Thanks guys for any and all input.
 

Attachments

  • DSCN5161.jpg
    DSCN5161.jpg
    149.4 KB · Views: 2

Woodonglass

Supreme Mariner
Joined
Dec 29, 2009
Messages
25,924
Re: Original transom does not meet flush with hull.what to do with new transom templa

I would NOT try and cut any pre-existing holes in my new transom wood. I would cover the transom skin on the outside with plastic and tape and then drill some air relief holes in the transom wood. (The Peanut Butter will fill the holes during clamping and the holes will ensure that no air get trapped between the transom wood and the outer skin.) You can build some inexpensive transom clamps like these...

PICT00185.jpg

or you can rig up some interior methods like this ...

(Click the Pic to Enlarge)

Clamp two by fours to the sids of the hull and across the bottom then nail wedge boards to it and wedge against the transom bottom. Does NOT take a lot of pressure.

Inside Transom Bracing.JPG
and you will get adequate clamping. You can then redrill any/all holes needed when you re-install the motor and other existing hardware.
 

Cadwelder

Lieutenant Commander
Joined
Aug 30, 2010
Messages
1,780
Re: Original transom does not meet flush with hull.what to do with new transom templa

Woodonglass said:
YD, Your wish is my command!!! It's GREEN Now!!!

Yacht Dr. said:
Saweeet .. Thanks and well done as usual .

YD.

You two are scaring me.....:) :)
 

derek23

Cadet
Joined
Aug 1, 2011
Messages
10
Re: Original transom does not meet flush with hull.what to do with new transom templa

i like your clamp system,makes sense,i think i'll go with the wedged 2x4s,c clamp/sandbag approach.
i didnt think pre drilled(3/4")motor mount holes might be an issue .i was planning on trimming the polyurethane glue that seeps in them later and then treating the holes.
what do you think might be an issue with what i had in mind?
thx again,just waiting for my plywood order and a grinder to smooth out those glass edges...not looking forward to the fiber dust,i do have respirator and gear though.
 

Woodonglass

Supreme Mariner
Joined
Dec 29, 2009
Messages
25,924
Re: Original transom does not meet flush with hull.what to do with new transom templa

I just don't like to take the chance that a pre-drilled hole might slip out of alignment.
 
Top