Transom Reinforcement for Outboard Conversion

[brittanydog]

Jim,

Thank You for your input on the CG question.

The owners manual says the boat is a 1982 2260, I havent seen too many of these around. Do you think the Volvo 4 cyl engine only weighs 200lbs?
I thought the old volvo motor we pulled was more in the 450-500lb area.

The weight according manual for the Yamaha's 200 & 225 is about 500-550lbs each, they are 2 strokes.
I havent picked a bracket manufacture yet. I'm looking at 4 sources - Armstrong, D&D http://www.dadmarine.com/, A&J Custom www.custommarinewelding.com and a local guy in Sumner that builds these bracket.

Looking forward to your progress report and pictures.

[Jim Williams]

brittanydog,

What I meant to say was 200# less than my old engine/sterndrive, but after better research it appears my new engine/bracket combo is about 20# MORE!

Volvo Penta AQ125: 396#
Model 280 Sterndrive 133#
total: 529#

Honda 150hp: 485#
OB Bracket: 65#
total 550#

Engine was bolted-on today, all went well.

Note: The Honda supplied bolts are too long for use on this type of bracket. The supplied bolts are meant for mounting directly to a 2-3" thick transom. Be prepared to purchase shorter bolts in advance of the installation.

[brittanydog]

Jim,

It looks great , I'm going to steal the plate and the angle brace idea. The Honda 150 4 stroke looks great also, I'm surprised by the weight, it weights the same as my 200hp Yamaha. Now come the rigging phase.
I want to fabricate my old engine cover and cut out the hump and make it flat and at the same level as the deck. I also want to create a good seal between the deck and the bilge. The strange lines at the transom and engine cover is going to make this a challenge. What are you going to do with your engine hump?
When do you plan to do the test run?

Louis

[Jim Williams]

brittanydog,

I'm currently searching for a 40"sq piece of aluminum or stainless "Diamond Tread Plate" to place over the engine hole. I should be able to make it flush with the rest of the deck and it will be a non-skid surface. I just need to determine what thickness (1/8" - 1/4") so it doesn't sag when I step in the center. For the inside vertical transom part I would like to construct something out of teak...maybe with a folding bait cutting table.

I hope to begin water testing in 3 weeks, just depends on how long the engine rigging takes???

Jim

[Elteqay]

I agree with Loveofsea, In my professional opinon you need to fill that hole with glass and wood and run the stringers into the transome.Beefing up the corners.

[Jim Williams]

I just realized that I never reported my final results!

My outboard bracket performed great, I have put about 100+ hours and everything works as I had hoped. I now get better fuel economy and a higher top speed.

Fuel Economy:

Old Volvo Penta 8gph @ 4000rpm (24mph)
New Honda 150 6gph @ 4200rpm (29mph)

Top Speed:

Old Volvo Penta 28mph @ 4700rpm
New Honda 150 39mph @ 5700rpm


I did get some minor porpoising but by applying some minor bow-down trim tab it was easily corrected. If you do this modification to your boat make sure you have trim tabs. There is nothing that I would have changed. My next project will be construction of a flat deck cover to replace the old motor "hump" cover.

[brittanydog]

Jim,

Glad it worked out for you, sounds like you have achieved the MPG saving and increase in speed as advertised.

I'm going to start my project this spring. Thanks again for sharing.

[naturewaterboy]

Jim,
Do you notice ANY difference in the sideways movement in big waves - moving the weight out of the bottom of the boat and adding some up higher - I'm doing a similar project with a twin engine boat.

[Jim Williams]

Naturewaterboy,

No difference. I typically operate in the mouth of the Strait of Juan de Fuca where swells average 6-8 feet and motoring with a following sea had the same amount of "tail walking" as the old volvo I/O . I have noticed that my turn radius feels wider, probably because the prop is 2' further aft.

[juiceclark]

You've got it right. I restored the first glass boat made by Wellcraft in Sarasota, FL. It was a twin I/O and I rebuilt the transom and installed a 6' Marine Stainless bracket and hung two Suzuki DF140s. To keep from just transferring the weight forward to the hull sides, I connected the bracket to the main stringers with two 3" aluminum bars and glassed over the bolts through the stringers.

It worked great...you couldn't even feel vibrations in the bars when in a choppy sea. Screw it down tight to take the weight off the transom even on hot days where the metal may expand slightly. You'll find the boat handles much better with the bracket. Here's the boat:

http://www.hsmarine.com/WellcraftAir...ners/TonyC.htm

[S Merrey]

Jim, I just acquired a 85 Bayliner Ciera Sunbridge 2450 and would like to do the same conversion, I plan to Fab it out of aluminum as we have a local custom boat builder up in Vicksburg MS near the old Le Tourneau site who can help me.
I still have not decided yet on one or two motors.
But I may also use the same setup as my bass boat with a hydraulic jack plate arrangement built into the conversion so I can better position the motor.
my model does not have a motor hump. I saw photos of one conversion where they put in a aux. gen where the I/O motor was; my plan is to add more gas tanks in that area also.
Give me your thoughts on this