Going from inboard to outboard same boat?

[starcraft guy]

Hello all,<br /> I have a 21 foot starcraft chieftain,It had a inboard outboard on it,I will be puting from a 40 hp to a 100hp outboard on it, I now have a 40 hp and a 60 hp outboards,and may want to go up to a 100 hp,<br />Now the transom is good and strong but i know it was not built to gang a outboard off it ,Would <br />braces going from the floor to halfway up the transom be strong enoughr to hold the weight?<br />Any ideas ? thanks river run

 

[crab bait]

Re: Going from inboard to outboard same boat?

was that a 'inboard' or was it an inboard-outboard motor..??

 

[bayman]

Re: Going from inboard to outboard same boat?

I'm not the expert on this subject but I do have a few points.<br /><br />1. There have been a few posts on this subject in the outboard forum. You'll want to check those out by searching for them. Wish I could tell you what to search on.<br /><br />2. I'd reinforce it as much as possible even though it may seem sturdy...especially if you go with a heavy engine. <br /><br />3. Connect a strong cable to the outboard and anchor it down to a good, strong place. The idea here is that if the engine does break loose then you have a back up. There are multiple reasons for this. The most important one is that if you get in an accident and your boat stops really quickly, the engine is less likely to fly on top of everyone in the boat. Nobody wants a fast spinning prop anywhere near them.<br /><br />4. Depending on the type of engine you had before this could change the center of gravity of the boat. You may find that it doesn't plane the same way and decide to get trim tabs or something like it.<br /><br />5. I'm sure I'm forgetting some things so be sure to find those other posts which are likely to be in the outboard forum.<br /><br />- bayman

 

[starcraft guy]

Re: Going from inboard to outboard same boat?

Thanks for reply<br /> It had a inboard-outboard, a G M motor with a volvo pinta out drive,

 

[crab bait]

Re: Going from inboard to outboard same boat?

the reason why i asked is cause an inboard boat has a paper thin transome.. an in/outboard has lot beef...yeah, i'd beef it up the best & INTELLIGENTLY as possible

 

[starcraft guy]

Re: Going from inboard to outboard same boat?

Thanks guys<br /> The transom is about 2in, thick and in real good shape, The outdrive don't seam to heavy , And i thought that a outboard might be to much without some braceing,I will brace it right from the bolts<br />that will be holding the transom mount, That should transfur the load to a larger area,<br /> thanks again<br /> river run

 

[clanton]

Re: Going from inboard to outboard same boat?

at least 2 knee braces from bottom of hull to transom. look a there 21 foot boat with outboard, you should be able to see the braces.

 

[DJ]

Re: Going from inboard to outboard same boat?

River Run,<br /><br />The Chieftain was also offered in an outboard model. If you look around, you will probably find one to have a look at. If you cannot find an outboard Chieftain, look for a 21' Islander, Super Sport or Holiday. They all used the same hull.<br /><br />FYI, the Islander was a Chieftain with a shorter, cabin and the Super Sport was a bow rider, while the Holiday was a closed deck runabout.<br /><br />Hope this helps.

 

[DJ]

Re: Going from inboard to outboard same boat?

River Run,<br /><br />Sorry for the double posts, but I just thought of something.<br /><br />Most of the Starcrafts of that vintage were powered with a 120 or 140 MerCruiser or OMC. Those engines were before prop. rating so they actually were about 100 and 120 hp., at the prop, respectively. And they did OK.<br /><br />You can buy a COMPLETE 3.0LX (135 hp. @ prop) for about $6,000.00. That's less than a comparable hp. outboard. The packages come complete with, engine, mid section, drive, guages, controls and even a prop. The transom cut out would be the same and probably the engine mounts also would be the same.<br /><br />Look in the ad sections of some of the popular boating mags. for ads from: Kenyon and Doug Russel Marine.<br /><br />I have also seen these packages on ebay.<br /><br />Two mags that come to mind are:<br /><br />www.trailerboats.com<br /><br />www.boating.com

 

[Bondo]

Re: Going from inboard to outboard same boat?

i've got a '74' islander, your going to want a bit more HP than your looking at now to be happy with the fruits of your labors..........<br /><br />with that said, i think it would help in your application to also tie the center,top of the transom to the inside gunnel panels....call them elbows, or arms.... they'll tranfer the top flexing of the transom beyond the stern plate to the full lenth of the hull...<br /><br />that's what i had to do with mine, after adding a 4.3LX, alpha 1, Land & Sea torque shift prop... the top plate on the transom kept popping out of the rub rail moulding....talk about torque?? this old tin boat has a lot of "we're outta here" left in it !!.....

 

[cannonfodder]

Re: Going from inboard to outboard same boat?

I'm in Saint John also. Get in touch and I will help if I can. I know enough to get in all kinds of trouble. <br /><br />Bryce

 

[johndezman]

Re: Going from inboard to outboard same boat?

could probably call starcraft and get them to sell you the appropriate bits then just drill and rivit in place.<br /><br />i had one of the old flat bottom 21' chieftans (late 60's vintage) and 125 outboard hp was "adaquate" - the 200 hp black max installed later mad it a **** of a ski boat! the 125 would top out around 34 mph pulling a 17" prop.