My bracket project

[Briguy]

Many of you have e-maied me personally about the installation of my motor bracket on my 23' 1978 CC. Here is an update:

Oh, where do I start. I have a 1978 center console 23' with 115hp suzuki's. I just put the motors on about 16 months ago. They give me a 30mph cruise at 4000 and top out at 43-44mph at 5900 rpm. Mine also has the 14x23" aluminum props. This power package is very fuel efficient and fast enough for me. Previously, my power was twin 130hp Yamaha's. I lost about 1kt at cruise and top top end. I gained about 35% overall fuel economy.

Now, about my bracket: The weight of the 4 strokes is a little heavy and that scares me a little. When offshore and it's rough, I get considerable water in the well and that only weighs the back end of my boat. My batteries are under my console. The solution, for me, was to install a bracket. I went with a SeaMount-Mattson dual motor, flotation bracket with a swim platform. It is 7' wide and has a 29" setback, the flotation chamber is 41 inches wide. The quality is very high. The cost was 2100.00 which was about 800 less than the same Armstrong. I looked at but didn't even consider the seamark due to the cost of about 4k. My hopes are, when I install the bracket, the waterline will rise(fall?) about 1/2 to 1 1/2 inches. It SHOULD NOT be any worse because of the positive flotation chamber.

Right now I stand like this: motors have been derigged(by my mechanic),(every other aspect has been done by myself) the motorwell has been cut out as has the floor. (about 2 feet of the stern) I left in tact the old bait well which I will be converting to dry storage with a hatch. The transom has been glassed in with 2 x 3/4 inch marine ply, 1 layer of biaxal mat between and 3 layers of mat on the inside and out. I used epoxy resin(about 4 gallons) at $60/gallon. The transom is now filled, and capped(corecell) to look like an origonal seacraft inboard 23' cap. I faired the heck out of the outside transom and sanded for about 30 hours as of now. 2 weeks ago I gave up and needed a break. Sunday I got back into it grinded some more. I dry fitted the bracket and noticed it did not fit properly. Not the bracket's fault but mine. The bracket is perfectly straight across the horizontal plane of the stern but the transom has a slight bow. (thus my grinding Sunday) I called Colon the owner of Mattson marine for some advice. He is VERY knowledgeable. I need to make sure the flotation chamber fits correctly.

http://www.seamount-mattson.com/twinplat.htm

(picture of the bracket) The final 12" on each end of the swim platform is where the gap exists. Colon said that should not matter except for the perfectionist. 5200 can fill in a 1/4 inch gap at the ends. I cannot do any more work inside the boat until I get the bracket mounted. (because it will be easier to bolt it on with no floor) Next I need to roll and tip the transom with Sunfast Red Awlgrip. Once the bracket is mounted, I can install the floor(corecell) and begin the fairing and sanding inside.(yuck!) Once that is done, the motors can be mounted and I will paint the inside with oyster white Awlgrip. My goal is to be finished is Thanksgiving day.

This has been quite a bit more labor than I anticipated. I have never attempted a project anything remotely close to this. Yes, I am sick, I am actually enjoying this. I dream about being out on that boat having people come up to me and inquiring about it. Performance? They all say you will gain 10% but I don't believe it. My old performance #'s are verifyed by gps and written down. If I gain anything, you will know about it. 10% would put me near 50mph top end: baloney. [img]images/icons/wink.gif[/img] Pictures? I don't have a digital camera. My trusty 35mm has been documenting everything. When she is done, I will let you know and have the pictures to prove it.

Brian Thomas

[John R]

Ouch! [img]images/icons/tongue.gif[/img]

But a well detailed version of this project will be a great help to a lot of other people in addition to giving you something to smile about when you look back on it.

I am also very interested on hearing how the roll and tip process comes out on the transom and how many coats & hours it takes too...

Goos luck with the "project"

[wildlifeone]

I have a 23 1972 i/o conversion with a 2000 ficht 225. and an armstrong bracket that I recently put on myself. i had the same issue with the curve in the transom. dont worry when you tighten up on the bracket bolts evenly it will all come togther with not much of a gap. 5200 willmake it look grwat. The stern of the boat came up 1.5 inches with wide body bracket. I didnt see any great increase in speed.I cruise at 4000rpm/ 32mph.and wide open 5700/ 44mph.the only thing I might caution you on is the height of the bracket mounted on the transom.On mine I mounted it about 1 inch higher than the specs and I still run my motor almost in the top hole. good luck

[Tom]

Like the other good advice, you should get 1.5" of flotation with the bracket. The lower you mount it, the more of it will be in the water giving buoyancy - but you may run our of holes to be able to raise your engines to the right height. Do the math carefully!. For every 12" of setback, you can expect to mount 1" higher than if on the transom.

It would probably be best to fair, finish and complete the transom painting prior to mounting up the bracket. It will be easier to get a good job laying out the awgrip with it off. I am not envisioning why you have to wait for the bracket to be bolted up...is there an acess problem on the inside?

When you rig the engines, use the yamaha grey hose and female fittings for the transom and mount them close to the centerline - this will give you more "walking room" on either side of hte bracket. Mount the hydraulic lines directly under the rigging tubes - both should be as high as possible to prevent water getting in there.,.

I disagree on forcing the transom to conform to the bracket. The bracket will not bend. period. This means as you tighten up all the bolts, you are forcing the transom to bend, putting tension on one side, and compression on the other. Start jumping waves with point loads, and these non-static forces, along with the loads of the engine, and something will move and crack. Its like torquing the heads on a motor - do it wrong and bad things happen. the 5200 will not fill voids and let you tighten up against the hardened sealant. I have made this mistake once, and am currently having to live with the solution...So, spend a few more hourse fairing and sanding now and do the job right, like you know in the back of your head.... good luck!