I have a 1979 20foot 201 Marlin I would like to remove my tired 4 cylinder and replace it with a double wide stainless bracket with (2) outboards totaling the same horse power or under the max horse power allowed, if so would and modification to the stringers & transom be needed. Thanks Bob
I/O to Outboard
- Thread starter circle hook
- Start date
Most likely the transom won't be strong enough. I don't think the transom is wide enough for twins. In addition, the balance of the boat will be significantly chaged with the removal of the inboard engine weight and the addition of all that weight off the stern. Even one motor would probably be an issue.
It doesn't sound like a good idea to me.
It doesn't sound like a good idea to me.
sounds right i didnt think about that but does the air cell in the stainless marine bracket counter for some of that weight they state it takes up on the switch from 2 strokes to 4 stroke engines thanks bob
Perhaps but not to make up the difference of 1000 pounds or more of motors hanging off it.circle hook said:
If you want to keep the boat repower it with a six cylinder I/O, you will be way ahead of the curve.
the reason going with outboards is i allways wanted twin outboards and the boat is free but the engine is shot and i have the twin bracket allready along with twin controls & cables with twin ing. switchs and (2) remote oil tanks and all gauges i striped a boat for some one and they let me keep all those parts and they are mercury so all i need is (2) mercury engines like 100 HP engines how much can they weigh, is the torque too much on the transon & stringers I can bolt the stringers to the transon with no problem & straight to the stainless bracket making them almost one. I am wondering if the transom is thick enough for outboards even small ones Thanks Bob
Your transom should be 1 1/2" thick which is strong enough for outboards (assuming is not rotted). The problem you will have is the boat was made to be used with an I/O, so not too much re enforcing was done on the transom. All you have to do (again, if the transom is solid) tie knees from the original stringers (assuming are not rotted) to the transom using EPOXY resin and using at least 1708 glass. When remove the engine clean all the old engine, remove the engine mounts and install two new stringers/knees combination between the transom and engine "room" front bulkhead(assuming the bulkhead is solid).
Oh, make sure you close the hole from the outdrive. :mrgreen:
....and while you at it, mind as well install two layers of 1708 glass on the inside of the transom overlapping the hull sides and the bottom (inside) of the boat by at least a foot. First layer overlap 12" , second layer overlap 15" is ideal.
Oh, make sure you close the hole from the outdrive. :mrgreen:
....and while you at it, mind as well install two layers of 1708 glass on the inside of the transom overlapping the hull sides and the bottom (inside) of the boat by at least a foot. First layer overlap 12" , second layer overlap 15" is ideal.
seasick said:
Yes. :wink: It's a very common practice to convert an I/O boat to single/twin outboards.
Seasick, once you mount that bracket the boat is going to be VERY sensitive to the weight hanging off the transom. I would recommend selling the twin rigging and mounting a single engine, or if you are dead set on going twin Mercs, look for some 90 hp inline six motors. At 285 lbs. a piece, you won't find higher power to weight ratio. I think the later 100 is a 4 cyl and is heavier than the I-6 and from what I've read the 3 cyl 90 has questionable reliability.
gw204 said:
The crazy part is putting twins on a 20 foot boat with an 8 foot beam, bracket or no bracket.
I am not the one proposing the conversion for the record
well after reading everybody's tread i guess i am going to drop the idea mostly knowing the age of the boat and the possibility of the transom being too week i guess i will wait for a larger boat to come along and maybe try again and start with one that comes with outboards allready the only thing i dont like about outboard boats are the ones that come with that transom cut out not a full transom backing down in the ocean i dont care for water comming tru that opening thanks guys bob