Twin 35's

[cannonfodder]

I am going to scrap my OMC V6 and 1977 electric shift and cut the transom on my 18 ft. cobia. I have 2 35 hp. Johnsons. Will these plane it. This should start a discussion. Open boat centre consol.Thanks for all opinions [*]null

 

[Walter]

Re: Twin 35's

Sure it will plane...but a single 70 will give you better performance and fuel economy. Plus, you won't have to butcher your transom.<br /><br />Walt

 

[mrm]

Re: Twin 35's

Go for it!!!!!!! sounds like the price is right. If both motors run good, might come away with a sweet rig. <br /><br /> Nothing venture-- nothing gain.

 

[cannonfodder]

Re: Twin 35's

Yes I do need to butcher. I might not have been clear on the existing configuration. It is one of those real bad OMC outdrives. I have already repaired it too many times. Parts are expensive and hard to find. It is as easy to make room for 2 as 1,plus I should always get home.

 

[Walter]

Re: Twin 35's

You mean it's an OMC "SeaDrive"?

 

[cannonfodder]

Re: Twin 35's

Right. The lower part has always worked fine , but the upper is corroded and always blowing up or getting water in side even after reseal session. The tilt and trim is weak even after a new $350.00 motor.

 

[Walter]

Re: Twin 35's

Oh..wait. I think I understand. It's an I/O, right?

 

[JB]

Re: Twin 35's

Hey, Bryce. Sounds like an interesting project.<br /><br />I wouldn't cut the transom. I would add a couple of simple, fixed jack plates. Cabelas has them for around $70-$80 each.<br /><br />That way you would leave a lot of options open if you are not happy with the outcome.<br /><br />It's danged hard to un-butcher a transom.<br /><br />Red sky at night. . .<br />JB

 

[cannonfodder]

Re: Twin 35's

It's got a big hole where the outdrive was anyway and I'm not shy of fiberglass. Anything is better than more gouging from the OMC junkyard. I can always get bigger o/b s. I don't want to go fast just for sure.

 

[Lark40]

Re: Twin 35's

Check the current copy of Trailer Boats.<br /><br />They have an outboard test of a single vs. twins of the same total power.<br /><br />The twins won in every respect. Surprising but true.

 

[masondr]

Re: Twin 35's

Swapping two 35's for a v-6? Sounds like a big diff. in HP. Re planing an 18', if an aluminum boat or skiff type hull, may be ok. If a wide, deep, heavy hull, may want to go for more hp. How did it perform with the v-6?

 

[masondr]

Re: Twin 35's

Also, re the single vs twins test mentioned, I have not seen it, but the only technical reason I can think of for those results is that the actual hp was not equivalent. I suspect that the twins were underrated and/or the single was overrated, or the single was not propped correctly. I would not want to generalize those results without an explanation.

 

[cannonfodder]

Re: Twin 35's

3.8 GM V6 versus 70 hp. It is fiberglass and relatively heavy,but it worked really good with the V6 (when it worked. It had a 3 layers of rotten plywood and stringers contributing to a big cup in the bottom ahead of the transom.I hope my repairs will fix all that and make it go easier.

 

[DJ]

Re: Twin 35's

Bryce,<br /><br />I think you might be surprised at how well it does. I'm just guessing but it definetely is interesting.<br /><br />As you know, that old GM/OMC V-6 was a better boat anchor than boat engine. I seriously doubt that engine had much over 100 hp. at the prop. and ALOT more weight to boot over twin 35's.<br /><br />I like JB's idea of brackets! It will allow you to get the engines up higher. Plus you'll keep a full transom for better seaworthiness.

 

[cannonfodder]

Re: Twin 35's

I will build a full width tub in front of the o/bs.I have been in the bay in my 14 footer and know what following seas look like. Plus I can't swim (always wear a PFD) as soon as I get near the water. Thanks for all the feedback. I really appreciate it.

 

[Franki]

Re: Twin 35's

I thought I'd pose a question at this point..<br /><br />I have a 17 foot half cabin, and presently, the last two feet of the back of the boat are wasted on a huge well for the outboards..<br /><br />I heard soemthing recently about changing to a pod system.. I have a 2 inch think transom in good nick, but to be able to get rid of the huge well would be fantastic.. (I might consider keeping the boat for longer as opposed to getting a new one..)<br /><br />Has anyone done this?? is it hard??<br />I can get the fiberglass gear, stainless steel reinforcement plates.. tig and mig weilders and obvoiusly marine ply.. but has anyone seen plans for something like this?<br /><br />Most of the newer boats seem to have changed to a pod system around here.. I'll have to get a short shaft outboard to use it, (or use an extension bracket) <br /><br />but that 2 feet of extra space would be fantastic..<br /><br />any tips of suggestions or comments or insults etc.. would be welcome..<br /><br /><br />rgds<br /><br />Frank

 

[cannonfodder]

Re: Twin 35's

I will be so happy to get rid of the engine in the middle of the floor that the well is only minor. If I were going to keep this I would go to a bracket/swim platform. The bay is big water and I will need something bigger in the end.

 

[cannonfodder]

Re: Twin 35's

Well, Nobody said anything to really discourage me so I will have at it. I will let everyone know how it goes. Thanks for all the replies. I just discovered this forum and think it is great.