metal transom plate

[mikemerrill50]

hey guys, somebody mentioned that they had heard of people having stainless steel or aluminum plates machined, for the purpose of strengthening the transom. i searched for this, but i couldn't find any results. they said this is done on high-powered speedboats. what they said is that you can get a plate machined to the size/shape of your transom, and this will allow you to run a higher powered outboard. in my case, i would be thinking of adding it just to allow additional strength, because I do not want to add a huge motor, nor could i afford it. anyone heard of this or done it?<br /><br />thanks!

 

[fishingdan]

Re: metal transom plate

I think simply adding a plate to the transom of a boat so that someone can overpower it is a recipe for disaster. You state that you don't plan to do that, but I felt that it was worth stating. <br /><br />The strength of a transom does not come solely from the transom core. The total strength of a transom is the result of a complete integration of the transom to the hull sides, hull bottom surfaces, the stringers, any transom knees, the motorwell/splashwell structure, the floor, etc. <br /><br />Why do you feel that you need to strengthen your transom? If it has been damaged or is weakened as a result of rot, it should be repaired.

 

[mikemerrill50]

Re: metal transom plate

naww, i'm building the boat from the stringers up. but a little added security won't hurt. i've stripped the boat down, and I will be doing the stringers next month. the next part after the stringers will be the transom, which I will be doing with seacast. i figure it can't hurt to add the plate (besides my wallet and a little weight). the boat was rated for 145 hp, and I would like to go to 150, but 115 or 125 would be just fine. this guy told me by adding a thick plate, you i could put 250 on it, but I wouldn't trust something like that!

 

[santa666]

Re: metal transom plate

Heck yeah! I'm rebuilding a 17 footer from the gelcoat in and wouldn't dream of not having one. <br /><br />Its not just a flat plate though- I've designed one with stress braces that extend out about a foot, to just under the splash well and bolt to/near the floor/ sringers for a multidimensional support device-

 

[mikemerrill50]

Re: metal transom plate

how much would something like that cost to have machined? and do you have any pics/diagrams? what do you know about increasing motor capabilities? give me details!

 

[fishingdan]

Re: metal transom plate

Since you are rebuilding from the stringers up, I would skip the seacast and rebuild the transom with traditional methods. <br /><br />See this tutorial for transom replacement...<br /> http://bateau2.com/content/view/144/28/ <br /><br />See this tutorial to get an idea of how a transom should be integrated with the other components...<br /> http://bateau2.com/content/view/75/28/ <br /><br />If the boat was rated for 145, 150 will not be a problem. It is easy to increase the strength with the above methods by adding an additional lamination of biaxial fiberglass (wider than any of the previous layers) on all seams. To add some additional stiffness to the transom itself, you could put a layer of biaxial between the plywood laminations or on the inside surface. <br /><br />The thing I don't like about using a plate is that your are limited to using mechanical fasteners which will localize stress.<br /><br />Just pointing out that there is another option.

 

[mulv80]

Re: metal transom plate

Mike, My dad has an 18ft Manatee and I have a 17ft Manatee. They are really well built boats ie: heavy. I would consider putting the highest recommended hp on her. With a 120 Evinrude she does about 33-35. A 150 will probably put her closer to 40-42.

 

[santa666]

Re: metal transom plate

Mikemerrill50- since you asked here's the details- <br />MINE will have 6 pieces, 10 holes and 10 welds- Not really machined, just flat planes cut and welded on 90 degree angles, etc...<br /><br />I can send you a JPEG which details way better than a disertation here- Please write me at dirkwalrich@hotmail.com and I will send you it. <br /><br />A flat plate will be OK, but for some rigidity it needs to have bracing. Sort of looke like an origami folded paper double wing fighter plane that's missing the nose cone.... <br /><br />Uh, better Just e-mail me, a picture is worth a thousand words-

 

[E. E.]

Re: metal transom plate

These are out on the market to help support your motor/transom. <br /><br /> http://www.iboats.com/mall/index.cg...*=37720898&search_in_category=f&view_id=40150 <br /><br /><br /> http://www.iboats.com/mall/index.cg...*=409272016&**********=37720898&view_id=20681

 

[mikemerrill50]

Re: metal transom plate

haha santa i'm emailing you now. EE, those might be what I heard about, and I those definitely seem like a good option (and also cheaper than what the guy was telling me about). he told me the plate covers almost the entire transom. however, i like what you showed me more (won't look as crude).

 

[Chris1956]

Re: metal transom plate

Mike, When I bought my Avenger Speedboat it came with 3/8 flat plate (Aluminum alloy of some kind)bolted to the transom. The plate nearly covers the entire transom. It also came with a 150 Merc inline motor. I found out much later that the boat is rated for a 90. The boat can certainly handle the weight of the 150 inline (same as 90 inline), but the operator must handle the extra power and speed.<br /><br />Anyway, you should be able to buy a plate to fit your transom (provided it's flat), either from a performance boat place or alternatively, buy a piece of 3/8" aluminum, and cut it to shape with a metal cutting blade in your Skil saw. Drill a few 3/8 bolt holes around the perimeter of the plate, and then use it as a template to drill the transom. Bolt it on with SS bolts and washers. Use caulk to keep it from leaking.

 

[santa666]

Re: metal transom plate

Just to clarify....<br />My design is on the INSIDE of the transom and has braces that extend to connect with the floor and stringers, which are of course appropriately sealed, etc...

 

[mikemerrill50]

Re: metal transom plate

i thought so, santa. chris, that's exactly what I have heard of. but santa, i want to look at your design also. both seem like good ideas.

 

[mikemerrill50]

Re: metal transom plate

i thought so, santa. chris, that's exactly what I have heard of. but santa, i want to look at your design also. both seem like good ideas.

 

[javsam]

Re: metal transom plate

yes, I added a 15x20 aluminum plate to my transom for extra strength. It only cost 20 dollars from a welding shop. and it was 1/4 inch diamound plate.the transom is rated 115 hp and I have a 125 hp mounted to it.<br />javsam