I have an 18' 78 Dyne in pretty good condition that has a single 87 Johnson 175 that I would like to put twin Mercs on. The problem is that standard motor spaceing for twins will not allow for the steering arm from the cable to move within the splashwell without hitting the side of the splashwell. I have several options: 1 - put a pair of manual jackplates in. This would allow the steering arm full travel. I have found the minimum jack plate set-back is 5" but with the extra weight of the twins 5" of set-back may not be a good idea. 2 - space the motors closer. Any experience here would be helpful. I think even a few inches of closer spacing of the motors would still allow that steering arm to impinge on the side of the splashwell - not to mention the motors hitting each other in a tight turn. 3 - re-build the splashwell. A pain but doable. 4 - get a different boat - there are a few out there but none have the classic bubble deck. And this one is paid for and it took a major effort to make my wife agree to my 3rd boat. Thanks in advance.... TJ
Straight 6 or V6 mercs? I just finished an 18 with twin 150 straight 6's and used hydraulic steering. Works real nice. If it has to be one of the 4 options, I'd rebuild the splash well. A lot of work, but a sweet rig in the end. Mike
That is one sweet ride. Could you please post some more pictures of it ? I'd be interested in seeing how you modified the splash well for the hydraulic steering. I'm curently building a 18 with twin V-6's and using the Sea-Star hydraulic steeering, and it appears there will be a neeed for a pocket to be fabricated into the starboard rear corner of the splashwell to accomidate clearance for the hydraulic cylinder bracket. I realize using the straight sixes gives you a little more leway on spacing the engines on the transum, so maybe you didn't have to modify it in that way. Any help would be appreciated. Bob
I'll post some pictures of the boat on another thread. I don't want to hijack this one. To your question, my motors are spaced 17" apart on center. With that, the cylinder mount clears the splash well by 1/2". A V6 would likely fit in the same space since the tilt cylinders are underneath instead of on the side like mine. I'd hang the motors on the transom as close together as possible, without bolts. Then install all the steering hardware. My guess is it will clear. I have a Uflex cylinder but the Teleflex should be the same width. I can only tilt up about 20 degrees because the cylinder hits the clamp brackets. Hydraulic steering was designed for newer motors that bolt rather than clamp to the transom. You could also cheat both motors over to the port side a bit to gain some clearance. With a light boat and that much HP, any performance loss will not be noticeable.
Sweet rig Ski! I am thinking that cheating the motors a little closer to each other and building a pocket on the starboard side of the splashwell to accomodate the steering arm is the way to go with the least amount of work. I know the standard top bolt holes for mounting a single is 13" (6.5" off center each) and that the standard twin mounting uses those same bolt holes to give the standard 26" (center to center) for a twin rig.
How about this for an idea? Instead of passing the steering cable through the starboard motor to the port motor and needing that steering arm clearance on the port side of the port motor - why not pass the cable thru only the starboard motor and have the steering arm between the motors and control the starboard motor directly and the port motor with a tie bar from the starboard motor? The master plan is to put 2 of the new very light Merc 150 4 strokers on.
Yes 910 for the pair. A pair of Opti's would be 862 and only lighter by 48 pounds. One battery moved behind the driver could mitigate that and a twin rig would have two. I do not see 50 pounds making a whole lot of difference. 2 up-front gas tanks instead of the one would totally balance the boat.
If you are spending that much on the motors, dig a little deeper and go with the hydraulic steering. There is no torque feedback from the motors on my twin 150 rig and it should fit your boat with no modifications. I have both cable and hydraulic steering on dynes and I'm sold on the hydraulic.
I have hydraulic steering on one of my other boats and am sold on it. I definitley plan on installing it in the Dyne.
