Tri-Cabin engine stringer question????

13footbeam · Post by **13footbeam** » Fri Sep 03, 2010 11:59 am

I was in the aft-cabin changing the port inline fuel filter (engine off) while under way in fairly rough seas (starboard engine pushing us about 8 knots) and I noticed the inside engine stringer (closest to center bilge) was floating up and down about 3/8 of an inch every wave we went thorugh, I could see this difference when looking at the stringer where it meets the upright that is mounted in the transom. I looked at the starboard side as well and they are both designed the same where the engine stringer ends and meets the upright mounted in the transome and neither seem to be bolted together or conected in any way.

My question is: should I be seeing this movement or has something let loose?

Thanks,

Pat

k9th · Post by **k9th** » Sat Sep 04, 2010 9:06 pm

I can't imagine that is by design. I have never seen one do that.

Sounds like your engines are under the beds in the master stateroom? Mine are under the salon floor and they don't do that.

rickalan35 · Post by **rickalan35** » Sun Sep 05, 2010 1:27 pm

Pat

....I was in the aft-cabin changing the port inline fuel filter (engine off) while under way in fairly rough seas (starboard engine pushing us about 8 knots)....you sound like me earlier this year when my starboard water pump impeller bit the bullet and I had to limp home 18 miles on the port engine.

Regarding your problem, my engines are also under the aft beds and I usually get down there every trip out (my wife at the helm) and take the engine side covers off in order to inspect with a flashlight for anything out of order like hose leaks, shaft bearings etc. I have never noticed any movement such as you've described in your post. But I have been watching the engines etc and not staring thru the rear hatch at the transom where it meets that stringer. I will hopefully be able to do so next week and report back to you.

The only other advice I can offer is to have it inspected when you haul it out.

Rick

sehord · Post by **sehord** » Sun Sep 05, 2010 7:23 pm

I have never heard of any stringer on any boat that has movement. The engine should be secured and not flex up or down , if so the shafts would wobble in the packing glands and struts and couse it to bind. check it out a little closer

turtlem1969 · Post by **turtlem1969** » Sun Sep 05, 2010 10:51 pm

I know on mine there are some thru bolts at that location then about midway up, there are holes where there were some at some point, and then the v-drive mounts bolts go all the way thru. But I can see all this because the engines have been removed along with the bunks, have to replace that set of stringers which are really just for the mounting of the engines, trannies and v-drives. hopefully that helps some.

jimbo36 · Post by **jimbo36** » Mon Sep 06, 2010 8:54 am

turtlem1969 wrote:I know on mine there are some thru bolts at that location then about midway up, there are holes where there were some at some point, and then the v-drive mounts bolts go all the way thru. But I can see all this because the engines have been removed along with the bunks, have to replace that set of stringers which are really just for the mounting of the engines, trannies and v-drives. hopefully that helps some.

Im thinking the stringers are the major structural component of the hull, along with the keel,etc, One solid piece, fore and aft. So, what have you removed? I can assure you, the stringers are NOT just there to bolt down engines

jimbo36

turtlem1969 · Post by **turtlem1969** » Tue Sep 07, 2010 9:03 am

On mine i have the actual structural stringers attatched to the hull, then running along the top of those are a set of stringers/engine monuts made out of 2x12s that the actual engine mouts are affixed to. which i believe is what Pat was referring to.

captainmaniac · Post by **captainmaniac** » Tue Sep 07, 2010 12:40 pm

Any useful info in this recent prior post re tri cabin stringer issues ?

http://www.trojanboats.net/wforum/viewt ... t=stringer

13footbeam · Post by **13footbeam** » Wed Sep 08, 2010 2:38 pm

Turtlem1969, you are correct, I am speaking of the 2x12s the engines and V-drives attach to, the lower one on the port side is the one moving a bit at the stern.

Captainmaniac, thanks for the link, there was lots of useful discussion in it.

Thanks to all and anyone that has made or may have suggestions.

I am going to take her out and inspect her some more and see what I can see.

Pat

Bob Giaier · Post by **Bob Giaier** » Thu Sep 09, 2010 8:22 pm

Captain Maniac, that was my posting earlier about my 73 tri cabin stringers. I've spent allot of time and effort repairing my outer stringers and forward bulkheads and am done as of Labor day week end. Once I actually take her on another sea trial I'll explain exactly what I did in that posting, since it's a different issue from 13 foot beam's

With 13footbeam, it sounds like the engine cradle may have broken loose from the stringer. From what I see on mine the engine mounting beams or engine cradle is held to the stringer with some 1/4 -20 brass carriage bolts and fiberglass resin and/or adhesive (not glassed). The stringers are fiberglass wrapped independant from the engine cradle.

On mine, to ensure no movement between the stringers and the engine cradle I added 3/8-16 stainless bolts in 3 in front and 3 behind the engines securing the cradle to the stringer. My cradle is approximately 1 1/2 inch x 12 mohogany faced on both sides with 1/4 inch marine plywood to make the 2 x 12. Although I didn't find any rot, I did see signs of delamination of the plywood from the mohagony especially around the V drives. I figured the added 3/8-16 bolts with fender washers and nyloc nuts would hold everything solid.

I will be looking at the whole area for movement this weekend and will look specifically at the stern attachment of the innner main stringers.

Hope that helps

13footbeam · Post by **13footbeam** » Fri Sep 10, 2010 9:28 am

Bob thanks for your input, it is very valuable, I love my boat and want to get her well again, I do not feel what I see is how it should be.

With 13footbeam, it sounds like the engine cradle may have broken loose from the stringer. From what I see on mine the engine mounting beams or engine cradle is held to the stringer with some 1/4 -20 brass carriage bolts and fiberglass resin and/or adhesive (not glassed). The stringers are fiberglass wrapped independant from the engine cradle.

I did not see these bolts you are speaking of, do they go through the hull?

On mine, to ensure no movement between the stringers and the engine cradle I added 3/8-16 stainless bolts in 3 in front and 3 behind the engines securing the cradle to the stringer. My cradle is approximately 1 1/2 inch x 12 mohogany faced on both sides with 1/4 inch marine plywood to make the 2 x 12. Mine is of the same designe.
Although I didn't find any rot, I did see signs of delamination of the plywood from the mohagony especially around the V drives. I figured the added 3/8-16 bolts with fender washers and nyloc nuts would hold everything solid.

I will be looking at the whole area for movement this weekend and will look specifically at the stern attachment of the innner main stringers.

Please let me know what you find and maybe you could post some photos of what your are talking about with the bolts you added. Thanks,
Pat

Bob Giaier · Post by **Bob Giaier** » Sun Sep 12, 2010 8:53 pm

I believe the 1/4-20 carriage bolts between the stringer and engine cradle that I was speaking were probably non trojan (the guy before me mmight have done that). They don't go thru the hull only thru both the stringer and engine support (cradle). to hold the 2 together.

I took mine out yesterday and watched the connection you refer to - that is where the main stringers meet the transom. Mine moves about as much as you you describe your movement. I did tighten the bolts that secrure the stringer to the transom before the sea trial, which must have done nothing.

It is the end of the season here in Michigan. I plan to let the area dry out over the winter and resecure and maybe glass the stringers to the transom with epoxy and biaxle cloth. Pat, I've done a ton of outer stringer repair and retabbing all over my tri cabin (look at the posting referred to in this one about tri cabin stringer repair). This doesn't look that hard, but I intend to get input from others more knowledgable than me before I do it.

Let's see what others have to say too.

13footbeam · Post by **13footbeam** » Mon Sep 13, 2010 10:39 am

Bob,

I believe the 1/4-20 carriage bolts between the stringer and engine cradle that I was speaking were probably non trojan (the guy before me mmight have done that). They don't go thru the hull only thru both the stringer and engine support (cradle). to hold the 2 together.

I looked again very closely at my setup and it is the same as yours, it has 1/4 20 brass bolts through both the stringer and engine cradle and the stringers are fiberglassed to the hull until you get with in 36" of the transome, then nothing, I would have thought they would have went right to the transome glassing the stringer to the hull????

I took mine out yesterday and watched the connection you refer to - that is where the main stringers meet the transom. Mine moves about as much as you you describe your movement. I did tighten the bolts that secrure the stringer to the transom before the sea trial, which must have done nothing.

Mine has no bolts securing the stringer to the transome upright stringer, not sure why???

It is the end of the season here in Michigan. I plan to let the area dry out over the winter and resecure and maybe glass the stringers to the transom with epoxy and biaxle cloth. Pat, I've done a ton of outer stringer repair and retabbing all over my tri cabin (look at the posting referred to in this one about tri cabin stringer repair). This doesn't look that hard, but I intend to get input from others more knowledgable than me before I do it.

Yes, I would think they would have done it already???

Again, maybe someone smarter then us can chime in.