Hard Dingy Transom Questions.

[Bad Obsession]

I have a hard dingy that I tow behind my Catalina 30. I use an island hopper 2.5 hp outboard from it. The transom holds that okay, but I have heard and saw a small crack on the transom. I am thinking about adding a little extra support back there as I want to find a nice used 2.5 hp two cycle outboard (Nissan, Honda, Johnson, etc).

I have considered fiberglassing a board back there that runs the width of the transom on the inside part of the transom (there is no way to add a board to the exterior part of the transom). Then I also considered getting a Teak or Oak board and putting two U bolts on the exterior of the dingy (could be used to attach a bridle to if I wanted to haul the dingy aboard) on the end parts of the transom and this would also bolt the extra support board in place. I may put a screw or two into the meaty part of my transom where the outboard sits to add a little more to it to hold it on there.

Which method do you think is best for adding a little extra support? I kind of like adding the nice board, varnishing it, attaching it with two U bots and screw, more than I like fiberglassing it.

 

[Ross]

The more completely you can attach it the better will be the load distribution.

 

[Bad Obsession]

I am not looking to support it enough to stick a 4 cycle on it at 40lbs. That would suck to take on and off of the rail of my boat. I would like to find a 2 cycle 2.5 that is water cooled, not heavy, and dependable. For some reason my air cooled island hopper concerns me for long bits of motoring and it is showing rust after only 2 years of use. It also likes to vibrate and knock parts loose and it is insanely loud!

That being said, fiberglassing it seems like a lot of extra work that I really don't want to do and the teak board or oak board would look nice. I am leaning that way if it will support enough to lift the dingy with the U bolts and hold the outboard.

 

[Anchor Down]

Done Deal

It appears you've already decided.

Fair Winds,
Jeff

 

[Stu Jackson]

The issue is support, Bad O

I understand not wanting to fiberglass (I've been able to avoid it for 25 + years!) and use Marine Tex in many places. So, if you've decided to use the board, think about how some very good marine glue or Marine Tex or other epoxies could add additional support to the screws and/or bolts you've thought about. Glue AND screw would work best. Good luck, we have a 2 stroke for our outboard and it sure is loud, too. I hear ya (sometimes only when the engine is off!) One of these days...

 

[Hermit Scott]

Do you have a picture? Is it convienent to hang it on the transom rail in any way? When I get a dinghy and motor, I thought of hanging it on the stainless rail on a board structure that I was going to make out of 3/4" thick PVC.
I can't wait to start doing some creative things on my C30, right now my mission is through hulls and seacocks. I always come on here with a bunch of different ideas on how to do things on my boat, then I just end up doing it the way they tell me.
By the way, I am glad to see you made it out of everything ok.

 

[Bad Obsession]

Thanks Guys. Stu...You have a valid point. I could glue the board in place and use C clamps to hold it there when it dries.

This board may cover part of my coastguard plaque so I may have to trim the bottom off of the board so that it doesn't cover the plaque.

The outboard always hangs on the stern rail on a plastic outboard mount.

The one downside of the 4 stroke is the stupid weight. 44 pounds for a 2.5 HP outboard is way too heavy. 20 pounds is about right!

 

[Hermit Scott]

That one took me a minute to get. I was thinking "why is he hanging a 2.5 hp motor directly on the transom of his C30?" I also thought " my God that must be a heavy motor to crack the transom of a 10,000 lb. boat"

I read it a few more times and then got it. lol

 

[Bad Obsession]

After a lot of things that I have read and heard about, I think that it is a big safety thing to carry an engine for the dink. If your regular engine dies you can always push the boat with the dink for a short while if need be. Just a thought on that one!

 

[Stu Jackson]

Good idea, but don't push or pull it

do a side tie and you'll have a lot more dimensional stability. Midship ties with the dinghy on the boat's quarter works best. Especially with a small outboard engine.

 

[pvanv]

If the dink's transom is failing, you may be, no, likely you are, overpowering the original design. If so, consider a different dink that can safely handle the OB. OB weight, in and of itself, likely has little (if anything) to do with the transom cracking issue, (though it sure would be a pain to haul a heavy kicker up to the pushpit to store it).

We run an ancient air-cooled Chrysler/West Bend 3.6 hp 2-stk OB on our Walker Bay 10 RID, and store it on our pushpit. Light enough to store on the rail, and powerful enough to haul provisions and 2 or 3 people. Unfortunately, the new Tohatsu OBs that I sell (lightest on the market) are all 4-stk, and heavier (but not ridiculous), so if you want more hp and light weight, look for a used Tohatsu/Nissan 2/2.5/3.5 2-stk. At 27 lbs, they are the lightest available in that hp range.

Your transom is likely failing due to OB thrust and torque, not weight. Is the dink rated for power? If so, how much? Perhaps the dink, if new enough, and you are within hp limits, is in warranty. It really sounds like you are over-powered, or the dink is defective.

If you reinforce the transom with a stout (white oak for example) board, encapsulated in, and fastened to, the transom with epoxy -- either marine tex or other, while fixing the stresses at the transom itself, you may end up overloading the joint where the topsides meet the transom -- to the point that you could start ripping the whole transom off the back of the dink.

Maybe a different dink is a better solution. A Watertender 9.4 ($500 new) will handle up to 5 hp. Our WB 10 with the RID kit is a lot more, but can go up to 6 hp no problem, and it rows like a dream.

 

[Bad Obsession]

This is an older dink that is rated for 2 hp. The outboard that I have now exerts thrust strangely on the transom because of the way it sits. Additionally, there really isn't much in that area of the transom and it could use some beefing up because a normal outboard has a 1.5 inch thick area to sit atop. Adding an extra inch back there would be a good addition. It definitely will not overpower the dink.

The reason that I want to go to a water cooled 2 cycle is that it is, in my mind, much more dependable for long dingy trips than my air cooled weed eater (An Island Hopper is a modified weed eater). The Island Hopper, in my mind, isn't holding up well to salt water use either as there is already some rust on it.

I think that adding a little marine glue and two U bolts on the transom and a few screws will be exactly what I want.