TOPIC: Power needed for Dorsett Catalina 19'?

My restoration project is puttering along nicely. My first priority was to replace all the rotted-out plywood in the transom, keel, and stringers. That is almost done and once I get the deck back in place, I can start on the more "fun" stuff.
I bought the boat without an engine and would like to start searching for the replacement. My question for the group is what horsepower should I be looking for? I don't need a speed demon, and am more interested in operating economy. But, I do want the boat to plane and be able to pull a single water skier. Top speed in the low thirties would be great. The boat is rated for a 150HP motor, but I hope I can make do with a lot less then that and still hit my goals.

Thanks for any suggestions you might have.

Bill

my catalina is the 16 1/2'. I have a 66 100hp Johnson that will pull a skier with no problem. I would think that will be the minimum for you. But just a guess. Pulling a skier adds a lot to the requirement.

Hmmm, maybe I need to rethink that bit about a skier. What if I just want to get up on a plane and hit 30MPH?

It can be a big math equation with lots of variables. I once did a cruise with my 20 foot 1500 pound rig using my big 30 pitch speed prop on a 200 v6 going about 30-35mph. Ran with a 15 foot MFG with a 75hp using a 15 pitch power prop they Ski with. Boat was maybe 1000 pounds. Both boats had 4 adults. They thought the 200 would use twice the gas... but I only took 6.5 gallons with the 200 and the 75 took 11 gallons to re-fill. They were red lining wide open at about 34-35. I was Maybe around 3,000 rpm instead of 5800 redline. If I would have used my 21 pitch ski prop, I would have used way more gas... My big prop was like a car having overdrive. Maybe an appropriate larger motor with the larger prop would give you economical cruising around low 30s when a 115-150 could do mid 40s if ever needed to beat a storm back to the launch... yet no one says you ever have to open the throttle on the bigger motor. The bigger motor could still pull one skier even with that bigger prop. A smaller motor with smaller pitch prop could pull the skier and likely do the low 30s, but might also run at higher rpm on plane at 30s and maybe then burn more gas at nearly wide open instead of half or three quarter throttle of the bigger motor. Cost of motor, reliability and if still can get current parts and service all factor in. The expert can chime in on goog motor options for year, brand, and hp. Do you want period correct or a good motor from mid 80s that can be decent on parts and power, yet not too pricey. Also remember older motors had horse power rated at the crank shaft and then changed to rating hp at the prop shaft. Merc changed around 1983... I believe OMC did that years earlier. A more modern 85 or 90 may have as much or more power than an older 100hp engine. Also have to ask yourself if tilt and trim is important over a period correct motor with no tilt and trim. I found a 1986 fresh water Merc 90 in-line 6 with controls and built in trim that I bought for a friend. Looked nice and runs nice. There have to be tons of OMC 85, 90, 100, 115, 135, 140 v4, and lots of Merc 115 out there so experts could chime in. Even some v6 150s our there from many brands. Right motor at right price... sometimes it takes time. I found the 90 at one of the antique Outboard event swap meets. Hope others with cruiser boats and motor experts can guide you closer. Good luck!

Thanks, Dr. Go. You'r right, there are multiple variables. One I can answer right away is the question of period vs. modern: At this point, I want to go with fairly modern - something like a 5-10 year old Evinrude e-Tec or Mercury Optimax. Down the road, I would love to hang a pair of period-correct 25's back there, but for now, I want reliability and efficiency

One thing you did not mention was weight. I saw a Dorsett Catalina brochure on line that stated the boat was rated for 150 max HP. From what I have been able to read, in the early 60's, that size motor came in a range of 180 up to around 225 points, so I would like to stay close to that weight to avoid riding too deep in the stern. A Gen I e-tec 50 HP weighs in at 240 pounds, and a 60 HP bumps that to 320 pounds. Weight might be my limiting factor - not too encouraging. But your comment about prop HP vs. shaft HP gives me some hope.

So here's my new question to the group: Do you think that a correctly propped modern 50HP be enough to get me where I want to be?

I didn’t mention weight until I got a feel of what direction you were going. I don’t know anything about the modern e-tecs or other modern motors around 50 or 60hp. The earliest single 150hp I remember was our Mercury 150 in-line 6 that had trim... experts can help, but I am thinking that motor would be close to 275 ir so pounds. That would mean the only way to get Outboard power in the early 60s would mean using twin 75hp engines... or close. That would be lots of tail weight. I have one of the lighter 200 v-6 engines with my 1987 Merc at about 365 pounds but I need to check that in the book. The v-6 150 would weigh the same. Mine still runs fine. I think about 1983-1987 is this somewhat smaller 2.4 liter v-6. Modern boaters have 75hp 4 strokes are physically bigger... people think it is a 2 stroke 75 because it looks small compared to modern engines. I should look up your hull weight before going further. Hope someone with your boat could pipe in. For larger engines with the 15 spline prop shaft, Mercury used to make a 2 speed shifting prop that help heavier boats plane out with a smaller pitch and then at a certain RPM, they would shift up to a larger pitch for better fuel economy at cruising speed. Not sure if you could find one or what engines they fit. I think I am getting off track for you, so hope some of the cruiser members can jump in to help. Maybe the 50-60hp can plane you out and get to 30s. But not sure you want a larger gas tank in back with battery weight when it comes to planing out. Doubt it would be fun pulling out a larger adult water skier without the help of some wide vintage skis.

From what I could gather from the library, it appears the 19 footers weigh around 1300-1500 pounds. Add a light engine, gas, and 2 adults and now likely over 2200 pounds. I would think a 50 hp engine would be laboring to get out and go. Maybe propped down to plane off nicely might leave you running near red line wide open and maybe high 20 range or barely edging 30 at wide open. I don’t have these combos, so others with similar rigs can help give you way better advice than me. When I think of future engine changes, then I think about either re-sale of first engine and how much depreciation I lose, OR I look at another project boat that the First motor would work well on once I swap the first rig to vintage motors. Just som thoughts.

Update:
I found A LOT of information by Googling "dorsett catalina weight". The third entry had four listings from this site, written seven years ago. There is also a good one from the N.W. Classic Boat Club. All of them were on the topic of what engine to install and the consensus was that a well-running 50 horse is all you need. Several people noted that the boat became unstable over 30MPH, so why put a bigger motor on it?
I found a Honda 60 HP in my area. The price is "decent" and the condition seems solid, and the weight is in the right area at 239 pounds. I will make an offer on that this weekend.
Thanks to all for your comments on this!

Glad you were able to find all of that good information. I knew my information was generic and not really getting to the root of the specific answers you needed. My old boss had a Honda if this size and loved it. Said it was a good motor for him. He did mention he fished on cold mornings and said cold starts were trickier for him and he just needed to let it warm up well before leaving the dock. I really like the looks of those Dorsett cruisers. Would be fun if I could use it more. Good luck getting the motor and hope it comes with controls, tank, and a manual as a bonus. I also ask if owners have any spare props they might throw in. The spare for one boat could be the primary prop for your boat.

OK, so this is Update II. I was all set to get the Honda but then found out that it was an extra long shaft (25") so that killed it. Since I was rebuilding the transom anyway, I could have added 5", but the idea of having 239 pounds up that high on what has been described as "a tippy boat" turned me off.
I think I found a good compromise. I bought a 2004 Yamaha 90HP from a reseller in So. Florida that buys trade ins from dealers, refurbishes them as required, then sells them on eBay. All-up, with controls, prop, tach, and shipping, it came to $4.5K. I know that I paid a little premium, but the claim was that it's professionally maintained yacht tender's motor and had <250 hours on it.
IF all is as claimed, this is going to work out great. 30% more horsepower, same weight, older motor but great reputation for the make/model. I will update the group as to how it turns out.