switching from single to twins...

[haakebecks]

I don't want this to become a thread about how today's modern outboard is bulletproof reliable and that a kicker and twins is a smarter choice. I don't want to hear that twins are not necessary, etc. This has been debated up and down and I think that both sides have their point.

I ask because I have an old friend who is interested in jumping into the fold and has found a pretty clean boat with a kicker and older single 70hp motor that has damaged lower unit. He would like to repower with twin 50s if he buys the boat.

Has anybody here repowered a c-dory 22 or 25 from single to twins? How did they handle the gaping holes in the transom? What are the things to look out for? Please school me here as I don't know anybody who has repowered a vessel like this before and I'm personally curious!

 

[Sunbeam]

I haven't done it, but I thought about it as I was in a similar position: I wanted twins but the boats I found with them were in rougher shape, as compared to a really nice, clean boat I found with a single/kicker. These are a few considerations I found when contemplating the change.

1) Engine mount holes
Old ones would need to be closed out and new ones prepped (to the good, you could overdrill/fill the new ones properly).

2) Batteries
I believe twins each use their own starting battery so you will have two of them vs. one. That may necessitate using the other lazarette (or maybe the area between the fuel tanks) since you will then have three batteries vs. two. Wiring changes would need to be made of course.

3) Secondary (external) water separator/fuel filter/fuel lines
May want to change or add a second filter if you want to keep the two fuel tanks/systems completely separate for redundancy.

4) Splashwell drain
Apparently the usual drain location (which is slightly to stbd of center where there is a molded in low area) will (try to) exit right into one of the motor brackets and does not work well. So for this reason the splashwell drain is commonly put in the center of the transom for twins (or I have seen it way off to the side(s)). So.... move splashwell drain.

5) Helm gauges
Obviously the twins will need at least an additional set (or two if changing motor brands/gauge styles).

6) Helm seat
The helm seat may need to be moved slightly inboard to fit in the second set of engine controls.

7) Steering
Not sure if this change would affect steering installation as I was going to go from cable to hydraulic anyway so didn't look at a straight transfer.

Since the boat I bought had such low hour engines (50 hours main/ 0 hours kicker), I decided to stick with them and see how I liked it; so I have not made the switch and don't know if I ultimately will. Once I get used to how my boat handles, I will probably try to spend some time at the helm of a boat with twins and then decide. (My main motivation was that I like the symmetrical look and smaller size of the twins, aesthetically.)

Sunbeam

 

[colobear]

your profile doesn't say where you are from but if you are in the PNW you might try contacting Les at EQ harbor Service for thoughts and advice. That would be my choice were I to undertake your plans.

 

[potter water]

For sure going to want hydraulic steering if it isn't in the boat. Moving one engine with that length run takes me a little muscle, but with two engines, I have hydraulic. Will have to get the electrics a little more complicated. Two start batteries probably and a house battery and the switches and VSR's etc to manage them. Probably would want to got to dual tanks, at least for more capacity because of being able to run 100 hp. But, not necessarily so. He may well already have dual tanks.

I'd go to a flexible linkage between the two engines. On engine gets the steering connection to the hydraulic unit, the other is slaved off that engine. Trying to run with on motor up out of the water in case of a failed engine, or for saving one when running with logs and whales makes steering VERY hard, even with hydraulic. I'm definitely going to replace the "hard bar" method of linking the two motors on my boat because of that.

I don't know what to say about the holes other than there are a lot of threads on the brats about the right way to fill and finish them so they disappear.

Of course, spacing between the two engines is important. I think that if I were going to re-power from single to twins, I'd leave it up to a pro boat shop to do. They will probably get it right. You will have to request the hydraulic steering and flexible motor to motor linkage.

Going with twins is great. It will cost, but the installation will be a small part of the total costs of the engines themselves.

Good luck to you and your friend. Besides the arguments about reliability and so on, the cool factor just requires twins on a C-Dory

 

[Chester]

Twins do not require two start batteries. A group 24 battery will easily start a 300 hp V-8. One each house and start batteries with a combine switch and ACR works well and provides redundancy.
Our no feedback cable steering works fine, no difficulty at all even with one engine raised. That said, hydraulic would be my first choice if going with all new components. Remember, the engines will need about 3/16" toe-in.
A couple different ways to plumb the fuel lines. My boat has one line with it's own Racor spin-on fuel filter (with see through bowl) from each tank to an engine. A valve could be used to pull the fuel from one tank at a time as well. Either way a good primary fuel filter is doubly important with today's fuel.

 

[Sunbeam]

Twins do not require two start batteries. A group 24 battery will easily start a 300 hp V-8. One each house and start batteries with a combine switch and ACR works well and provides redundancy.

Ah, good to know. The twins setups I had seen all happened to have two (smaller) start batteries plus the usual house battery, but now I learn that is not a requirement.

 

[redbaronace]

Fairly new here but will respond as my previous boat which was an Arima 19' had twins (honda 45's) and we repowered to a single motor / kicker combination (Yamaha 115 / Yamaha 8). I liked that configuration much better.

I can tell you that moving this direction is quite easier in that there are less parts involved in that swap than when going to twins. The reasons have already been discussed (more parts and more modification). Given that many would find twins on a c-dory a toss up or even less desirable, you may want to get the estimate for the conversion before making the decision to purchase the boat.

If your friend is planning to keep the boat for a long time, the higher cost of getting what he wants might be worth it. I for one would not change to twins having had them previously. Then again we just got a tomcat24, so what do I know.

 

[Chester]

Ah, good to know. The twins setups I had seen all happened to have two (smaller) start batteries plus the usual house battery, but now I learn that is not a requirement.

When it comes time to replace my group 24 house & start batteries I will look into getting a smaller start battery to save weight. The boat has 40 hp twins.

 

[colobear]

We went from two gp24 start batteries to AGM motorcycle batteries for our two Honda 40s (Les Lampman suggestion). That cuts the weight quite a bit and they both fit into a single gp27 holder. We have had that setup for two seasons now with no problem at all. Since we cruise long distances away from marinas we are battery heavy, we have two gp24's in parallel for house and the two small motorcycle batts for start. One gp 24 and both mc's are in the port lazarette, the other gp24 and battery controls are in starboard lazarette.

 

[potter water]

To press my points only slightly. Spending the money on twins makes a super nice CD22 setup. AND spending a little more to take full advantage with the hydraulic steering and separating the start and fuel systems and filter systems is better. But I've come from a belt and suspenders background of assuring reliability. Cutting corners to make an adequate instead of excellent installation after spending so much on two engines should be considered carefully. I've given careful thought to using MC batteries, but discarded the idea solely based on my belt and suspenders thinking that if the House battery goes, then I still have good house capacity using one of the group 24 starting batteries.

But, in practical terms, if batteries and systems are well maintained, almost any concoction of batteries and fuel systems and so on will do the job with twins or singles. If you consider your car or truck, how many batteries are there and how many engines? Only one. And you can listen to a lot of stereo and do lots of starts, and even do poor maintenance on that car or truck with very low probability of ending up on the side of the road.

 

[Sunbeam]

Cutting corners to make an adequate instead of excellent installation after spending so much on two engines should be considered carefully. I've given careful thought to using MC batteries, but discarded the idea solely based on my belt and suspenders thinking that if the House battery goes, then I still have good house capacity using one of the group 24 starting batteries.

If you are referring to Colobear, I didn't get the feeling it was about cutting corners so much as it was about considering needs/uses, and then, given the parameters, being efficient with space and weight (and proceeding on that basis, vs. a cost basis).

To me it came across like this:

1) Two lightweight starting batteries that are plenty adequate to start the engines.

2) Then devote the space/weight for a good, two-battery house system (for their style cruising).

This way the "spare" house battery is in the house bank all the time, where it can be efficiently used.

Sunbeam

 

[potter water]

Amen!

 

[Chester]

I Like to have back up and redundant systems also.
I want to reduce unnecessary weight in the stern. Thinking out loud it seems you only need enough battery to reliably start one engine. Once one engine is running I 'spose it could boost the battery to start the other engine.
My 90 hp Harley has a battery much smaller than the group 24 and the 40 hp Honda has a pull start (ugh) to assist starting with a low battery.
Sorry for the thread drift.

 

[rogerbum]

Like Chester, I never had any issues with hard steering using a teleflex cable steering system with my twin honda 40's on the previous 22 - either with both engines or just one engine in the water. So if expense is an issue, I would argue cable steering is just fine. A cable system is simpler and easier to maintain. Sure, over time the cable will break but over time the hydraulic seals will fail too. In either case, it's good to have a plan (like duct taping a boat hook or paddle to the engine) that will allow for steerage when that happens (of course twins can be somewhat controlled by throttle alone). That said, if one ever wants to install an autopilot, hydraulic steering is a much better way to go.

 

[potter water]

My C-dory came with hydraulic steering. I take all at their word what a CD with mechanical steering would do. My 26 foot mini houseboat had mechanical steering with a single engine merc 90 and it took muscle. My CD with the twin Suzies and hydraulic steering is smooth as silk with both engines down, but if I raise one enough to clear the top of the prop, steering becomes very difficult. So, I may have some geometry problems with the linkage. That said, I've read on this forum that others have struggled with single engine steering when the other twin was up, and went to a different engine to engine link that was itself, I think, hydraulic. I'll be looking into that this year as nothing would make me feel sillier than boating around in logs and sand bars and rocks with a twin engine boat and both engines hitting the obstruction, leaving me stranded.

 

[smittypaddler]

I have twin Honda 40s on my CD22, with mechanical Teleflex NFB Steering to one engine and the other slaved to it with a Stearns Auxiliary Motor Steering Kit tiebar. Maybe it's because I've never experienced hydraulic steering, so I don't know what I'm missing, but I don't find my setup particularly difficult. With both engines down I can put my palm against the steering wheel and rotate lock to lock with no problem. I notice some more resistance when running with one engine and the other tilted out of the water, but it isn't a problem. The only problem I had was the dealer I bought from installed a freshwater tiebar, even though I told him I'd be in saltwater part of the time, and I had to replace it after nine years of use. You can see photos and a description here:

http://smittypaddler.com/tiebar/

 

[colobear]

I didn't take Potter Waters comment as a challenge, just his opinion. My decision to use MC batteries had more to do with weight and more house capacity than anything else. As for redundancy; I start with two engines, two MC batteries either of which can start the engines, two house batteries either of which can start the engines, an emergency parallel switch which would allow me to parallel batteries and top it off with pull ropes (which really are hard!). Then I top that off with a 30W on-board solar panel that can get a charge in my small battery with not too much trouble. So, lets see two engines: redundancy, two start batteries: double redundancy, two start batteries plus house battery: triple redundancy, two start batteries plus house battery plus second house battery: quadruple redundancy; two engines plus two start batteries plus two house batteries plus emergency parallel switch, plus pull ropes plus solar charger plus, Jeez I can't count that high. Oh and did I mention the dinghy motor!! :lol: :lol:

 

[hardee]

Barry Barry,, I I love love your your double double duplicate duplicate redundancy redundancy.

You you are are good good. :lol: :lol:

:thup :thup :thup :thup

Harvey Harvey
SleepyC:moon SleepyC :moon

 

[hardee]

My two group 29 deep cycles provide plenty of start and house power with using only 2 batteries and each can start one or both of the twin 40's plus I only have one switch to remember to turn... and it is usually on "both". I do carry a separate jump start battery but have never used it on my boat.

Harvey
SleepyC :moon