What Holds the Transom to Boat?

[atengnr]

What is responsible for holding the transom to the rest of the boat under a load from the engine?? Is it stringers? The hull? The hulls sides? All of these?

I understand that the transom reacts the loading from the engine, but Im not sure where the transom is supported by the rest of the boat.

Thanks

 

[Chinewalker]

Re: What Holds the Transom to Boat?

No easy answer, or single correct answer to your question...

Yes, all of the above. Some light duty boats only have the sides holding the transom in place. No knees, stringers or keel used - think a lightweight aluminum boat or dinghy. Moving up the scale a bit, some might have a transom knee to brace it in the middle, possibly more than one to distribute the load a bit. Further up the scale are hulls where the stringers and keel act as knees. Many boats have floors that are bonded to the transom, in addition to the aforementioned parts. Many boats have a motor well included as part of the topsides, and this, too can add support. Some boats, such as Boston Whalers, have the transom moulded right into the structure of the boat.

Better to have too much strength in the transom than not enough...

- Scott

 

[andy6374]

Re: What Holds the Transom to Boat?

The strength of the transom really comes from the fiberglass skins that encapsulate the transom core (most like wood). The inside skin of the transom is tabbed to the hullsides and the bilge. The stringers also provide support as well.

So the skin provides much of the strength and it's the wood core that prevents the skins from warping. That's why we just don't use chopped mat when creating a inner skin of a new transom, it's just not strong enough, instead we use heavy fabrics like woven roven, stitchmat and double/triple/quadruple bias stitchmats.

Any sort of aft fishboxes, tabbed decks, ect.. also provide additional support

 

[General0]

Re: What Holds the Transom to Boat?

I've been having that same question floating around in my head! On my boat it seems that the rear raised bilge area is the only force keeping the transom in place? I've decieded to add additional stringers in the bilge area (there are non now to distribute the load a little better than just the floor holding it in.

 

[atengnr]

Re: What Holds the Transom to Boat?

When replacing the transom, how does one bond the new transom back to the hull sides, outer skin??

 

[andy6374]

Re: What Holds the Transom to Boat?

If the transom is replaced from the inside, then bonding it to the inside of the hull requires using peices of glass that are the size of the transom + a few inches. This will cover the transom and part of the hullsides/bilge. Make each layer consecutively longer.

After that I like to add additional tabbing between the transom and the hullsides/bilge.

 

[sam03v]

Re: What Holds the Transom to Boat?

I have the same question. I bought a trailer that came with a free 15 foot fiberglass boat, early 70's homemade. At least the title says homebuilt, I'm still not sure about that. Anyway, I decided to to fix the boat. The transom had been repaired at least once before, and looked a little funky...so i drilled some holes in it and sure enough mush came out with the drill bit. I didn't like the way the transom was repaired so I got crazy with the sawsall and cut most of the transom off, including the water splash tray(or whatever its called). I literally cut the back of the boat off. Then I cut off the floor. Turned out there was only one stringer in the center(mushy on the inside), the others were "passive" stringers(no core). Now I've got a very similiar looking boat floor as the one in the picture General0 posted.

My question is.. can the new stern/transom just be fiberglassed to the hull sides and stringers or should I try to make and fiberglass a frame on the inside of edge of the hull sides for the stern to be screwed to, then fiberglass over that? Or should I just scrap the boat? I'll attach some pictures as soon as I can.

 

[Solittle]

Re: What Holds the Transom to Boat?

Pictures will be a big help. Also what kind of power are you planning on? Dropping a 70 hp on the back will require a lot more beef in the transom than a 9.9 hp.