TOPIC: Transom rebuild

Previous owner put too large OB on Pacific Mariner Stiletto. Transom has separated as a result. Want to rebuild and reinforce. Any advice, tips, suggestions?

More on the list, but that's the starting point.

Thanks!

BillM2,


1st, WELCOME ABOARD.- GREAT folks here & GOOD info.

To give you advice, everyone will need good-quality pictures of the boat/transom/damages.

yours, satx

If you can get a trace of the original outline of the transom and make a new one (laminated) you could insert it into the hull. Make an outline from 2x12 or smaller of the outer hull and glue and clamp the transom to the hull. Use fairing compound or the like to set in place, the transom. With 6" strips of cross hatch glass, glass and resin in the inside where the transom meets the hull. Fair the outside, sand, glass and resin the outer hull. Some photos would be nice.

I rebuilt the transom on my G3. I pulled off the deck to do it, which made access really easy. The hard part was getting the old/rotted transom out and ground off the FG hull.

My transom is curved so I laid up the 5 layers of 3/8" plywood in place, gluing each one to the other with Weldwood (let each layer set before putting in the next). When they were all in, I filled around the edges with fairing compound as CraigLam suggests, then finally glassed the side/bottom edges with a bunch fiberglass strips and put two layers of cloth over the interior face too.

I dont have any good photos of the process, just some after it was in:

Oh, and be sure to seal the plywood edges well! Water will soak in like a wick otherwise. I used thinned resin which soaks into the wood, then sets... did it to the edges of each layer of plywood before it went in. I use the same treatment for holes I drill in the plywood transoms too, before I set the bolts with 3M 5200.

Bill, I'm doing a transom rebuild on my 1959 Glastron. there are some pics in my thread under "Member's Projects".

The recommended process is to cut out the interior glass layer and remove the plywood from there. If it can come out in one piece (as mine did), you can use that as your template. Sometimes a couple of pieces can be put together for a template. Other than that, you are in for some drawing on a large piece of cardboard.

I had a straight transom so I used two layers of 3/4" marine grade fir plywood. Everything has been encased in at least 2 layers of epoxy. The edges at least 3 and the top of the transom probably 5 (if I have leftover epoxy from another project, I put it on the top.) That was epoxied to the exterior layer of glass on the transom. I put 4200 on the edge of the transom piece and the edge of the hull before I installed it. After everything cured, I filled any gaps with a good marine grade filling compound.

In the next step, I epoxied 3 layers of fiberglass cloth around the edges where the hull meets the transom. Each piece of cloth was larger in size.

The next step is to fiberglass the inside. I plan to use 2 layers of Biaxial cloth (was the plan for this weekend, but didn't get to the shop before it closed). I am also adding a knee brace from the stringers to the transom, which has been built, but will be installed as the last step. A knee brace can add a lot of additional strength.

I have taken a bunch of pictures as I have gone through this and have posted some. If you need, I can either post of send you some more. I am far from an expert as this is my first transom, but between the advice from here and trying to understand how it SHOULD go together, I have made good progress.

Also, look to see if there were any design flaws in the transom and correct them here. Mine had a 3/4" gap between the bottom of the plywood and the fiberglass hull.

Good luck and I hope we hear about your progress.

The transom is pretty solid in itself. It has seperated from the top of the boat, however. I'll try posting some pictures>

I don't think I need to cut out the entire transom but rather sister some material against it (epoxy, hardware, glass), glass in that material to existing solid hull. There's an area to cut away that would give me access to the inside. [img] [img]http://www.fiberglassics.com/media/kunena/attachments/legacy/images/transom2-20120922-2.jpg

Now that is an awesome looking boat. Love the transverse lines.

Andrew

BillM2,

I strongly suspect that there's nothing that you can do for a permanent FIX except popping off the deck & repairing the whole transom and/or possibly a "design flaw".

in >4 deades of "messing about with boats", i've not seen that problem, except where there is either:
1. a design defect/flaw that has to be "re-engineered"/re-designed
AND/OR
2. a rotton transom.

yours, satx

The transom feels tight when pulling and the plywood sandwiched between interior and exterior glass isn't flaking in the holes. The separation or bowing out slightly away from the deck appears to have been caused by the oversized outboard. The PO installed mounting brackets to allow for better placement of the 60 HP motor. This, I think, caused an unusual pulling away. I think some marine plywood of an inch or so, epoxied with some stainless, sealed thru bolting, will sustain a 40hp outboard for quite some time. I don't think I need to cut away anything to achieve this.

Any other thoughts?

BillM2,

You know i've been thinking about this "problem" (i wasn't busy this PM) & wonder if i don't have an acceptable solution. = IF i was doing this (w/o popping the deck), i would get two long pieces of chain, at least 4 heavy "S" hooks & a pair of strong turnbuckles & TRY to S-L-O-W-L-Y pull the transom toward the bow, alternating the tightening of the turnbuckles.

IF that worked, i would leave it at least overnight & then make at least three "knees" to fit the port/starboard/middle-point of the transom.
Then i would "ease up" on the tension, install the knees to the inboard side of the transom with suitable (3/8 or 1/2 inch diameter) stainless steel bolts, lock-nuts & fender washers.
Then i would "butter" the surfaces with a coat of UNthickened epozy, a thick coat of "peanut butter" & then i would tighten the turnbuckles again & bolt everything else together. The remainer of the project would be "repairing the cosmetics", i.e., filling holes & refinishing.

I THINK that that "patch job" will work & support a 40HP OB engine sucessfully, presuming that you CAN actually pull the transom back into place, W/O further damaging the hull.

That's my "best guess" & a "SWAG" is ALL that it is.

BEST WISHES, satx

Thanks everyone, good input. I thought of pulling towards the bow with a come along or two. The gap is 3/16" or so. I could pull, set, install an interior transom board, glass, etc. The contours of the deck and hull at the transom are a bit tricky to attach to, and fortunately out of sight.

A couple thoughts on Satx's idea:

What do you pull against? The motor well seems in the way of and straight line pull attached to anything on the boat. Given the tension that is involved, you need a straight pull so as not to damage anything.

Turnbuckles are better than a come along because you want the micro adjustment to get the location right and not over stress.

Given the depth of the motor well as a percentage of the depth of the transom, can you place a knee under the transom that will be effective holding this repair?

If I were to do that, I would get a couple of 2x6s and drill holes that align to the two bolt holes for the new motor. Get a couple of bolts at least 3x the depth of the transom and create a sandwich, but do not tighten down. put a large screw eye in the center of the interior 2x6 and pull against that. That would pull on the transom without pulling on the deck.

There may not be rot now, but given where the cracks are, water (rain and transom overwash) has probably gotten in there and rot will set in eventually.

This is a very cool boat and worth a good restoration. I have a feeling pulling the deck and doing it right is going to be your best solution. Not sure where the deck seams are given the shape so it may be tricky, but ultimately worth it. Not sure where you are, but if there are people nearby who have taken off a deck before, it might be worth having them take a look or help.

Good luck with it. Very cool and worth the effort.

Just looked at your profile and you are in New Paltz, NY. Good collection of NE/NY people on this site.

thetudor; BillM2,

EXCELLENT POINTS. - fwiw, i'm not even sure that my SWAG will even work & still believe that "popping the deck" is BEST.

yours, satx

While I am not trying to be a kill joy here. If there is that big of gap at the transom some thing has been compromised that usually means the transom is soft. Now this is easy to check. If you have a good ear take a hammer and go on the back of the transom lightly tap wyou can hear the difference in a solid transom and wet one. Another way to check is with a drill and an 1/8 inch bit. Go on the inside and drill a hole about three guarters deep NOT ALL THE WAY THRU now look at the drill fiiflings clean like new wood that's good brown to black well that will be the reason you have a gap.


D

Satx -- congratulations on your 500th post!

I think turnbuckles the best device to pull. I could attach to the seat boxes, which are very sturdy, could be reinforced, and see if that will hold without splitting the wood. I could straddle the outer interior hull area floor with 4 X 8"s braced back to the transom, then attach the turnbuckles to that but that too may be problematic. There are some rounded metal studs sticking up through the hull about a half inch, as part of the boat's framing, perhaps something with those. I dunno....

Removing the deck seemingly only really gives me access which I have. What other benefit in this fix would taking it off produce?

Here's another picture of the rear. A boat repair guy said he would remove all the green fiberglass that extends from the transom forward about 24", and reinforce, glass again. See the picture here and above.

I think you meant to write 1/8 drill bit? I can certainly do this. Thanks!

BillM2,

I hate to be the bearer of bad news but... Don't you hate those BUT'S!!!!! In my Humble Opinion Your transom has been compromise and must be replaced if you want the integrity of your boat to be sound structurally. The Wood core of the transom should be tabbed to the sides and bottom of the hull with resin and glass from top to bottom. Based on the posted pics of your stern, I see no way to gain Full access to the transom without removing the top cap or at the very least cutting away the splash well. A Sound transom of a thickness of 1 1/2 inches and properly attached will support the weight and torque of a 120 hp. motor without issue. I highly recommend you read and study the following... forums.iboats.com/showthread.php?t=518300

If the guy is going to have remove the back 24" of green deck, why not replace the whole thing?

What removing all or part of the deck will give you is access to the top and inside of the transom. The deck and splashwell create a cap which needs to be removed in order to get at it. Here's a couple of pics from my Glastron which show that

thetudor; all,

I can assure everyone that the deck on the 1959 Hurricane runabout (that i've mentioned several times on the forum) will be removed & the floor, stringers & transom will be gutted & replaced with MDO, sealed/bedded in peanut butter.
(i once SAW the whole transom come out of a speedboat, at over 35MPH, on Caddo Lake in northeast TX & the boat went down like a rock, in 2 pieces. - NOT an activity that i would care to participate in!)

yours, satx

Probally a little late response. But, if the transom is solid and just the problem is the gap. Instead of trying to rig a pulling turnbuckle, maybe a jack to push it into place? Secure the boat softly, and a jack with a cross piece to put it back into place.

Never to late to join the discussion. Thanks, and yes I thought
about pushing evenly across the transom and attaching new glass to it and the hull.

Upon.closer inspection, I think the gap is between a wear layer and the transom. It doesn't appear to be bonded entirely to the transom itself at the gap with a 3/16" gap only in the sections I'm showing in the pictures. It's like an 1/8" thick plastic covering and surrounding the transom.

How thick is that transom?
It looks a little thin!
Is it 1.5" or a little less maybe?
It is kind of a small boat, but I don't think a 60HP should have killed it if it was rated for 40 HP. What is it really rated for?

There's no plate nor info online I can find specifying top HP. Based on weight and the size of the boat, a two stroke in the 40hp top range seems appropriate.

According to the Pacific Mariner brochure in Glassic Library, a 1961 Stiletto is rated for 50 hp. www.fiberglassics.com/wiki/images/f/f6/Pacificmarinerb61004.jpg

A 60 hp motor should not have broken the transom on its own. perhaps a little impact somewhere along the way?

If you want to fix the boat correctly, please heed the advise of the experienced folks that suggest a full replacement. If that undertaking is too intimidating (it is for most people) the boat can probably be used for many seasons before the transom gets too soft to use. Once the fiberglass around the inside perimeter of the splashwell starts to get stress cracks, you know the transom has to be replaced. Fill the gap with silicone or maybe some 3M 5200. This will slow down the rate of water getting in the core.

Because the top edge of the transom bows to the middle - it is indeed failing. That is a tell tale sign. The transom will never regain its original rigidity no matter how much goop or additional layers you try to patch over it. There is a 99% chance that there is rot in the core all around the motor mount holes, drain tubes, and anywhere a screw was drilled into the transom.

Most of these boats were built very light, and the transoms too thin from the factory. They have seen better days.

You can buy some time by bolting a length of sqyare metal tube across the inner splashwell. Cut it to fit against the transom face - and use the bolts for the ski tows to draw it up tight. The square tube us very rigid & will reduce the flex in the top edge.

Ti has been my experience with issues like these is that your tranosm has been compromised. Most likely, water has been leeching into your transom and it is rotting from within to some degree. A light tapping with your hammer on the transom will indicate and issue. A dull thud will indicate some degree of rot.
Think about the age of the boat, and how mauch it has been trailered. I see so many ourtboards in a tilt position when hauling down the road ad highway speeds. The engine that is unsupported and in a tilt position acts as a folcrum and adds undo stresses to your transom, constantly working back and forth on the top of the transom. This in my opionion is as much force or greater than the actual forces when in use on the water.
This is a neat boat that is deserving of solid repair. I always ecpect the worst when tearing into a hull project, then I am rarely disappointed!
A repair done properly will give you piece of mind....I think I would tend to want to pull the deck and replace the transom...

So took a closer look and the hull is glassed to the deck. So in order to do a transom rebuild, I'll have cut away the engine well and work that way. I'll use 3/4" marine plywood to get to 1 1/2", epoxying them together then glass to the hull and the deck, putting in gussets and glassing over those as well. Will also thru bolt in four places attaching the hull's shell to the new transom. I'll save the engine well piece and reattach where it was.

How's that plan sound?

I think that you are on the right track. I know you did not want to get this complicated with the project, neither did I with my Glastron, but it is ultimately the right thing to do.

If you know where your transom penetrations are going to be, you can locate them on the new core, drill them out oversized and fill the holes with epoxy. Then when you drill, you are going through the epoxy and not the wood, further protecting it. I don't have a motor yet, so I don't know where those holes will be, but I do have 3-1" drains; one at the base of the transom and 2 for the spashwell. Once I made the transom piece, I put the it in place and marked where those holes would be. Then I drilled 1-1/2" holes (hole saw being my weapon of choice over auger) in those locations and filled them with epoxy. On the attached picture, you see two dark circles about 6" down from the top; those are the plugs for the splashwell drains. The bottom drain has already been drilled. Yet more work, but a permanent fix for protecting penetrations.

Also, when all is said an done, get a transom protector for trailering. It locks the motor to the trailer and prevents it from bouncing, as 72hornet mentioned. Use them on all my boats (with outboards)

This may be a situation where Seacast would be a viable option.
I know a lot of the experts use wood here, and likely I would have too if I was on this website when I did my refurbish.
Is the transom 1.5" all the way out to the edges of the boat or is it only thick in that center section?
It is such an odd (but nice looking) shaped boat, working on this will be challenging, but fun I'm sure.

Unless Pac Mariner got carried away with bonding the deck to the hull, I stronly encourage you to split the boat. As horrible as it sounds, splitting is often less work than any other option, and it will absolutely net the best results. Having the deck removed makes doing the work infinately easier. Cutting the deck or cutting the back off the boat means a lot of work, and the strength of the hull will be reduced. It takes a ton of time and skill to graft a deck back together so that it looks perfect.

The tabbing that bonds the deck to the hill may only be 1 layer thick. I usually use a sharp chistle for wood and a hammer to cut the tabbing. If you can find an edge of the tabbing to get under, get a flat "wonderbar" and havver it under the tabbing to pry it upward. If you are careful, you can get the tabbing to "peel" away from the hull, sort of like peeling a bumper sticker off of a car. Get some clear pictures of the deck joint & post them for comment. Does the rub rail cover the deck joint? If so, remove that & show pictures of it without the rub rail.

Ultimately it's your choice on how to do it. But I am speaking from experience having pulled many boats apart, over the years. Others with experience will weigh in on this to try to help you as well.