Sig 300 Bad Stringer and motor mount

Roady68

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Sep 17, 2016
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I posted on the post started by drewm3i about an issue I fond with my Sig. The survey found some wet wood on one stringer and we negotiated the price accordingly (extremely attractive price for what we got, so no real regrets, at least not yet). I figured we would run the boat a year, and I would tear into it after next season. Well, I guess the plan has changed. The structure under the motor mount has cracked. My guess is that the cold temperatures we have had caused the water to expand. So, I have read several of the posts here and watched the friscoboaters videos. So I think I have a handle on the work ahead. At least on a high level. I do have some interesting constraints. First, the Admiral will kill me if the boat isn't ready for this summer. So time is an issue. Fortunately I have insulated Carharts so I've started working now. Second, the logistics on where its stored and being wrapped make pulling the engine impossible for now.

I will post some pics as soon as I figure it out on this forum (looking for the link on how to, any ideas?). But the plan is to do the demo work with engine in place for now. This is the furthest outside stringer assembly on the starboard side. I say assembly, as it appears to be two parallel stringers that run from the transom up to the first bulkhead up to the fuel tank. One of the stingers then continues up to aft berth/salon area. The wood is very wet and I am still looking for source. I though it was a leaking support from the swim platform. But looking at the foam and the overall amount of water in the wood, I am thinking something else may be letting water in. One possible path is the hose feeding the A/C unit. It appears to run up under the decking that is under the seats in the salon. A leak here would feed that cavity that these wet stringers reside. The rest of the boat is bone dry. Thanks ahead f time for the assistance.
 

GA_Boater

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Click on the Forum Help in the sig below and look at the Photo Upload Tutorial. That will get you started on attaching some pics, Roady.
 

Roady68

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Sep 17, 2016
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Stringers exposed.



My plan is to remove the fuel filter/separator, the sea water pump and the related hoses/lines. This will open up the area to be able to work. At least to get the demo work done. Doing the glass work to retab the stringers may be too hard to do with the engine in. Or leave the inside fiberglass "wall" and peanut butter the stringer in. As you can see, the stringers are not glasses in under the deck.
 
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drewm3i

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Dec 31, 1969
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Wow, that's a crappy build job (no glass, only gelcoat? really Chap?)...your best bet will probably be to do as you are planning. Maybe cut everything out now and have it glassed after you pull the motor? As for your leak, have you thought about the trim tabs? Is your transom full length? Hope not as it could be soft too if the tabs were leaking.
 

GA_Boater

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Roady - What's the transom like? Rotted stringers often go hand in hand with rotted transoms.

You have your work cut out for you to get on the water in 4-5 months. All too often these jobs stretch out and miss deadlines.
 

Baylinerchuck

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Looks very familiar. What year is your boat? My Chap is a 1990, and the motor mounts and lay ups look similar. The stringers were glassed in mine, just not well. I found it way easier to not have to work around the engine. Good luck on your build, I'll be tagging along for moral support.
 

drewm3i

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Roady - What's the transom like? Rotted stringers often go hand in hand with rotted transoms.

You have your work cut out for you to get on the water in 4-5 months. All too often these jobs stretch out and miss deadlines.

I would agree, but he can give it a shot. This is on a 30' cruiser with twins. I believe it is a '99? The transom and stringers are made out of XL marine pressure treated wood. I've found that this prevents rot from spreading on these Chaparrals (post '96). Depending on where the water intrusion came from, I think his transom will be okay.
 

drewm3i

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Looks very familiar. What year is your boat? My Chap is a 1990, and the motor mounts and lay ups look similar. The stringers were glassed in mine, just not well. I found it way easier to not have to work around the engine. Good luck on your build, I'll be tagging along for moral support.

Either a '99 or 2000. Only difference is his has XL PT wood vs. douglas fir marine ply. This is his model boat:

833225_0_030820102058_3.jpg
 

tpenfield

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It is 'funny' how boats can look great on the outside and not so great on the inside . . .

Anyway. . . It is unusual for a boat to attain moisture in the outside stringer areas without it being somewhere else first, like the main bulkhead. So, my first comment would be to take some core samples low and center on the main bulkhead and the transom, as best you can reach. Also, I assume there is a center stringer(s) for the 'inside' engine mounts. I would do a core sample on that as well . . . low towards the keel.

If, after those additional samples, you truly have an isolated issue, I would put a board (or two) on the hull under the engine and use a scissor jack as best you can to take the load off of the starboard engine mount (of the starboard engine). Then remove the engine mount along with all of the other 'stuff' that you mentioned. I would keep the exhaust manifold in place as that will probably where you can get the scissor jack to wedge, between it and the engine block. Make sure the jack is secure (a bottle jack may also do the trick, if not a scissor jack). Make sure not to raise the engine, just get the weight off of the engine mount.

You can then open up the engine mount itself by cutting out the top of the glassing. I would leave the sidewall glassing in place, as mentioned, and probably the stringers and cross members. Then let it dry out. . . you may want to apply some heat to this area to help dry things out. . . (make sure to apply safety precautions of heating things in the engine bay as fuel is nearby) Remember, the wood will pull moisture from other areas as it dries out, so it may take a while. You can then plan out the details of the rebuild, once you have a better look at things as they dry out.

Since your boat has the Greenwood XL plywood, the wood should not be rotting, but you may want to double check.

If you think a 3D model of the structure would help, I'm happy to make one, if you can post enough pictures from various angles and depth perspectives throughout the engine room and anything else that you can get the camera pointed at.

Be prepared to have the issue be more than you anticipated . . . they usually are.

Questions ??? for the areas of foam that you removed so far, was the foam wet? was there residual water in the area after you removed the foam? Is the bulkhead tabbed to the hull in the area that you exposed?

Timing wise, you certainly have enough time to get the boat ready for summer, if the repair is limited to this one engine mount area. It is a matter of how much time you have to spend on a weekly basis. FWIW - My bulkhead replacement (which went about 3X of my original plan) took about 6 months working mostly weekends and holidays.
 

Scott Danforth

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I would pull the motor (about an hour job) vs trying to work arround it. You have to re-align it any way since the mount is compromised
 

Roady68

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Sep 17, 2016
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Roady - What's the transom like? Rotted stringers often go hand in hand with rotted transoms.

You have your work cut out for you to get on the water in 4-5 months. All too often these jobs stretch out and miss deadlines.

The hull has the extended v-plane. The transom is actually three pieces. The two outside pieces are about 2" further out than the main transom that the outdrives bolt too. The main transom is dry. I have moisture meter (same one the local surveyor uses) and the Surveyor confirmed my readings when he did the survey. The transom at the end of the section that my picture shows is wet for sure. When I removed the swim platform about two shot glasses of water dripped out of the holes. That was my first thought of where the water intrusion was coming from. But those holes are above the decking covering the stringers. You can see light poking through the three holes in the second picture I posted. The foam was wet in spots. About 1/4" if foam from the hull up was wet. The foam between the two stringers (near where the fuel filter is) was soaked all the way. And in fact was still frozen. Its a pretty good insulator. The tops of foam was pretty dry except where the foam butted up against a stringer.

Its almost as if the cavity got flooded at one time. It also looks like someone was into the structure. There was a hole cut into he stringer and it looks like it was epoxied over and painted grey. I found grey overspray on batter tray and hoses. Looking at the parts list pictures for a 2003 Sig 300 (basically the same boat) that I pulled of Chaparral's site, the battery trays and hoses were installed after all the glassing in.

I have no option on dead line. Admiral will have me court marshaled and put in the brig if boat misses this season. Fortunately, I have weekends and most evenings open now that the holidays are past. Plus 6 weeks vacation. If I burn some days up working on the boat, so be it. I am usually scrambling to use them up at the end of the year anyway.
 

tpenfield

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I see the three holes in the transom/foam now that you mention them. I would think that it may be the way water got into the structure perhaps, as their location is within the stringer/foam chamber? :noidea:

Also, I am wondering if the bulkhead forward of the engines that the engine room stringers run to is wet, since water likes to run 'down hill'. Is the fuel tank just forward of the bulkhead and is it foamed in or only strapped in?

I think your time schedule is something like this:

2 weeks investigating and planning
2 weeks disassembly, demolition, prep work
2 weeks drying
2 weeks rebuilding
2 weeks re-assembling

So, maybe mid-April to be done with the repair.
 

Roady68

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Sep 17, 2016
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tpenfield, good idea on supporting the engine. The gantry crane I have access to is too narrow as the boat has a 10' beam, and the crane is only 8' inside posts. I thought about modifying, but I like the idea of supporting from the bottom. I'm not sure if I mentioned it, but the boat is all shrink wrapped for winter. The gantry idea would have made me cut through the plastic which could be an issue given our very windy winters. I also thought about a support from gunwale to gunwale, and use a small come along to raise that corner of the engine, but I am not sure gunwales could take partial load of an engine. I'd hate to crack the fiberglass up top too.


I will be taking measurements this week to make some additional supports for the underside of the hull. Currently there is blocking under the keel in two places with additional supports at the outside edges of the hull at the transom and about two thirds the way forward. I'd like to get a couple of boards like a bunk trailer, under the area I will be working. Hopefully the snow isn't too bad this weekend so I can get that done. If it is snowy, I'll pull the filter and sea water pump and start clearing out parts from the inside.



Anyone have an idea what a fully dressed Mercruiser 5.7l engine weighs?
 

drewm3i

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279
Fyi, check the trim tab...a leak there would fill that cavity with water.
 

Roady68

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Sep 17, 2016
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Fyi, check the trim tab...a leak there would fill that cavity with water.

I'll be cutting back tot he transom soon to get back there. It is one of two ways I see that water can get in. As I mentioned, the other is the A/C supply line.
 

Roady68

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Sep 17, 2016
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Roady, any update?


Well, it was much warmer this weekend so I had a chance to work on the boat a couple of hours. I removed sea water pump, alternator, fuel filter and the brackets on that side of the engine. It looks like it will be tight to work on the stringer and motor mount, but doable. I need to get the pictures off my phone and will post later. What I can see is that the stinger is wet, but not rotted. However, the boxed structure that the mount sits on is soft and delaminating. I am going to support the engine this weekend. I am adding supports under the starboard hull under the engine area to transfer the weight of the engine to the ground (think of it as sandwich the hull between the outside supports and inside support so no forces are transmitted to the hull). My plan is to rebuild the mount and reglass it in. The stringer is only glassed in on one side. This boat had a deck that covered stinger. I have had the stinger exposed to air for a month now and it is definitely dryer than when I cut open the deck. But still pegs the moisture meter. The deck section I cut off has been in my garage for the month. My garage is heated and the deck section is dry. Meter reads it is dry. So it is possible to dry the wood out. Just need the right environment. I am trying to figure out how to introduce the right environment now. I still have a couple of months before I need to get boat into the water. I am thinking of adding solar powered fans.

I am not able to pull engines at this time. It isn't an option. I am not too worried since the wood is wet, not rotted. The chips I pull out from drilling are wood colored, just wet. No black from the stringers. I am also not sure how water got into that cavity, so any work I do may be in vain if I haven't stopped the leak. I will be checking the water supply tot he A/C unit, as that hose runs under the deck, and checking the screws that hold the trim tab. My original though was that water was laying on the deck and passing through the screws holding the battery trays and trim tab pump to the deck. But those holes do not go through, so that probably isn't the source. I'll get some pics up tonight.
 
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