Transom problems with Larson 186 SEI I/O Bowrider

[JASinIL2006]

Hi all, I have a '97 Larson 186 SEI I/O bowrider, powered by a Mercruiser 350 Mag engine and an Alpha One Gen 2 outdrive. The drive train was replaced within the last year or two and functions great. We bought the boat last Spring (2012).

Yesterday, while prepping the boat for an outing, I noticed a bolt for the transom-mounted ladder bracket was loose. In investigating how to reseal and tighten it, I did some disassembly in the engine compartment on the starboard side, and I found some badly rotted wood on the transom. (See this thread that has some pics and more info: http://forums.iboats.com/showthread.php?t=570636 ) To recap, after moving some breather tubes and other stuff, I found some really soft, rotten wood in the transom on the starboard side, about six inches from the point where the outdrive goes thru the hull. The fiberglass on the rear of the boat looks great, and there is no movement when I put weight on the outdrive.

I don't yet have any idea about the scope of the problem, because the engine compartment is carpeted on either side of the engine itself, and the interior of the transom is mostly concealed by a carpeted piece of plywood. The wood on the interior of the transom seems OK on the port side, as far as I can tell now. Given how bad the rot is in the spot I tested (I was able to reach in and grab a handful of rotten wood with my fingers), I am assuming I have to replace the transom. I've read a lot of threads here where people have found themselves in similar situations and I think I'm up to doing the work myself. I don't have a lot of experience as a mechanic, but I'm pretty handy and I'm willing to give this a try.

I am feeling a bit overwhelmed, though, and I'm not sure where to start. I have decided our boating season is over, so I am guessing I'll also need to do whatever end of season maintenance/winterizing is necessary to make sure the engine and outdrive are OK. My goal is to have the boat ready for next year -- is that reasonable? I have a two car garage, but I will most likely not have a heated workspace available over the winter (I live in west-central Illinois), so I'll need to get done what I can in the Fall and the Spring.

So what am I facing? Where do I start?

Thanks in advance for your help. I have a feeling I'll be hanging around here for a while...

Jim

 

[bear_69cuda]

Re: Transom problems with Larson 186 SEI I/O Bowrider

Hi Jim,

Sorry for the bad news, but this forum can help get you dialed back in! For starters I suggest reading this thread... http://forums.iboats.com/showthread.php?t=454460&highlight=frisco+sea+ray

 

[JASinIL2006]

Re: Transom problems with Larson 186 SEI I/O Bowrider

Since I'm done boating for the year and plan to start working on this, I imagine I should do winterizing and maintenance on my outdrive and engine, yes? I had planned to take my boat somewhere for end-of-the-season maintenance and winterizing, but if I have to pull the motor and drive, would these be things I could do? For example, an oil change of the engine (while it's sitting in the boat) isn't something I thought about trying, but if it's sitting on a stand in my garage, might that be something I could do myself (since I would have to worry about filling the bilge with oil)?

I'm in the process of building a stand for my outdrive and engine, so I can work on the boat, but I'm not sure about what (if anything) would be easier to do now while the boat is assembled vs. when the engine and drive are sitting out.

Any tips?

Thanks,
Jim

 

[Woodonglass]

Re: Transom problems with Larson 186 SEI I/O Bowrider

This should be of interest...
http://www.lakeconroemarine.com/Boa...iser_Engi/winterize_your_mercruiser_engi.html

 

[JASinIL2006]

Re: Transom problems with Larson 186 SEI I/O Bowrider

Thanks, Woodonglass, that looks helpful!

 

[JASinIL2006]

Re: Transom problems with Larson 186 SEI I/O Bowrider

Well, I've winterized and pulled the outdrive... time to pull the engine and get at that transom! Never pulled an engine before, but Friscoboater and others have inspired me! I may actually be able to do this.

 

[Woodonglass]

Re: Transom problems with Larson 186 SEI I/O Bowrider

If you know anyone in the Wrecker/Tow Truck business or want to call and see what they'd charge, a lot of guys have used them to pull the motor and set it on a stand. Should'nt cost that much. Good alternative if you don't already have a method.

 

[JASinIL2006]

Re: Transom problems with Larson 186 SEI I/O Bowrider

Well, I've got my engine pulled and I've stripped everything off the inside of the transom. I've been reading lots on transom replacement threads, but I am not entirely sure how to get the old transom out of the boat. Here's what it looks like. The first picture shows the starboard side of the transom. (The green line separates the clearly rotten part from solid wood.) The second picture shows the starboard side of the transom and engine compartment with the carpet lining pulled back.



The worst rot is around the through-holes for the swim ladder. It looks like water has been running down the transom, onto the engine compartment floor and into the bilge. The floor on the starboard side of the compartment has a fair amount of rot within the two feet closest to the transom, but not much beyond that towards the forward part of the boat. I chipped a hole in one of the softer spots in the floor and the foam directly beneath was dry.



I know I'll need to inspect into the foam and stringers back here more thoroughly, and I need to expose the port side of the transom (which feels extremely solid everywhere I can reach it) and see what the engine compartment floor looks like over there.

As I start taking out the transom, how exactly do I remove it? The rotten part will be simple, but what about the intact sections? I'm worried about damaging the hull.

Also, before I tear out the transom, should I be making a template of it with cardboard or something similar for when I fashion the new transom?

Anything else I should be thinking about (or doing) at this stage? I've already ordered protecive gear (Tyvek suit, respirator, goggles) and I'm planning to get a 4" grinder.

Thanks!
Jim

 

[JASinIL2006]

Re: Transom problems with Larson 186 SEI I/O Bowrider

Bump.

 

[JASinIL2006]

Re: Transom problems with Larson 186 SEI I/O Bowrider

I'm a bit stuck right now... or maybe I'm just unsure as to how I should proceed. I've cut away some of the bad decking from the engine compartment on the starboard side. As you can see, the transom is pretty punky on this side of the boat, and the foam was damp, but not dripping wet, near the bottom. I'm still hitting damp foam at the forward end of the hole, so I need to take up some more deck and see what things look like as I move away from the transom.



What has surprised me is that I haven't found wooden stringers... there were no stringers supporting the deck near the side of the hull; the deck wood is tabbed to the hull, but there is nothing supporting it other than foam near the starboard side of the hull.

I'm also not sure of what to make of the support that runs along side the bilge (marked with red arrows in the photos below). It is part of a large fiberglass pan, it appears, that forms the floor of the bilge and engine enclosure.



This seems to be a fairly substantial fiberglass structure (stringer?) that has a foam center. I did a core sample on the foam in this structure and it came out dry. Of course, my hope is that the stringers in the boat are not wooden, but that is more based on my desire not to tear up the entire boat than anything else.

I'm not sure if I should try to leave this stringer (if that's what it is) intact, or if I need to remove it to get better access at the transom. There is a about an inch of clearance between this fiberglass structure and the transom core. (The transom was tabbed into the fiberglass 'stringer' before I started chopping away at the transom.)

Does anyone know what I'm looking at? Does this look like any kind of familiar construction that might provide clues as to how this thing was built or do I need to start drilling holes all over to figure out what is underneath? Or worse, do I need to just start sawing into it? I don't like the idea of chopping up something that may still be good.

Any ideas?

Thanks,
Jim

 

[Georgesalmon]

Re: Transom problems with Larson 186 SEI I/O Bowrider

Your stringers may well be made of foam. Not unusual Was it covered with fiberglass? If it was that's good. Typically the foam was used as a form for the fiberglass stringers and the fiberglass provided most of the strength. If its in the way of transom replacement remove as much as you have to and try and save it for reinstall if you can. If you can't save it you can replace that section with glassed over wood. Remember its just a form for the actual fiberglass stringer hat section.

 

[Woodonglass]

Re: Transom problems with Larson 186 SEI I/O Bowrider

I agree ^^^. Looks like Foam Engineered Stringers. Cut out with Sawzall if needed and Keep it for reinstall later.

 

[JASinIL2006]

Re: Transom problems with Larson 186 SEI I/O Bowrider

Non-wood stringers would be good, yes? Do I need to cut them back any further than necessary to get at the transom area?

Thanks,
Jim

 

[Woodonglass]

Re: Transom problems with Larson 186 SEI I/O Bowrider

Make it easy on yourself. No more than necessary. Have you core sampled the Motor Mounts?

 

[JASinIL2006]

Re: Transom problems with Larson 186 SEI I/O Bowrider

No, not yet. The lag screws that came out were not easy to remove, so at the very least, part of the mounts were intact. I don't think the screws were stainless, though, as they were a bit rusty (not severely corroded, but not clean and shiny). I didn't see any evidence that 5200 or anything had been applied to the screws, either.

To core sample, I just drill some holes into the mounts, maybe from the side (i.e., from the bilge area), and look for signs of wetness/rot/dark wood?

 

[Woodonglass]

Re: Transom problems with Larson 186 SEI I/O Bowrider

Correct, from the side, down low. 1/4" bit 1 1/2" deep. If shavings are light colored and dry you're good to go. When reinstalling Use stainless and DO coat with 5200. You're on the right track.

 

[JASinIL2006]

Re: Transom problems with Larson 186 SEI I/O Bowrider

Good to know! Thanks!

 

[Woodonglass]

Re: Transom problems with Larson 186 SEI I/O Bowrider

If They ARE dry, then fill the holes with 5200 and you're good to go!!

 

[JASinIL2006]

Re: Transom problems with Larson 186 SEI I/O Bowrider

Well, this is interesting... I drilled some holes into the motor mount from the bilge. I started by drilling a hole low on the starboard mount, near the floor of the bilge (see lower holes, circled in red).



Of the four lower holes, none hit any wood, even when the drill penetrated a full 2" or so into the mount wall. The fiberglass seemed to be pretty thick where I drilled the holes.

Next, I drilled a couple of holes higher (labelled A and B in the photo). Hole A is about an inch below the forward lag screw hole for the motor mount and hole B is about 2" below the spot where the aft lag screw on the motor mount is located. I hit dry wood when drilling both holes. The wood was fairly light (not like new wood, but like seasoned wood.)



The wood shavings actually look darker in the picture than they did when I had them in front of me. I didn't see anything that looked like rot or darkness, and the shavings were totally dry.

I drilled similar holes on the port side mount, and found the same thing. Wood from the upper holes looked fine, and the lower holes hit only fiberglass.

Does it make sense that I didn't hit any wood below the mounts near the floor of the bilge?

I also drilled a hole in the starboard stringer about an inch down from the top from the bilge side, centered between the transom and the motor mount. I got no wood shavings from that hole, only fiberglass. That fiberglass was pretty thick, too.

I didn't have enough time to take up more decking and remove additional damp foam, but that's next.

Thanks for any thoughts about what I'm finding here.

Jim

 

[JASinIL2006]

Re: Transom problems with Larson 186 SEI I/O Bowrider

One more question... to remove the section of the decking nearest the hull (center of the picture below) are there any techniques to cut up close to hull without penetrating? Or do I just have to grind all that off? I don't know that I'm good enough with my Sawzall to get closer without messing up the hull.




Thanks!