repowering my sailboat- engine selection

[Chinook92]

hows it going?

so.... I have a Catalina 27, picked it up for 1000$ and have subsequently gutted it, replaced all the bulkheads, plumbing, and currently doing the systems. my boat is an outboard model, with the well in the stern, and I have a great 15hp Suzuki on the back, but, I would need to hack up the transom to get it to tilt up which I don't want to do. I started thinking how much nicer it would be if I found a small diesel to stuff in there, and have all the luxuries of a diesel engine (like hot water, and that any time any where diesel reliability), but most importantly a charging system for my battery bank.

that's probably no easy task for your average boater, however, I am indeed a marine diesel mechanic, and install, fix, maintain, and repower boats for a living, so, for me personally, glassing in some engine stringers and fiberglassing in a stern tube, and sealing off the transom really isn't a big deal to me. I work at a boatyard, and have every tool in the industry at my disposal, and my boat is even on the hard there, so, its a pretty sweet deal, and given what I have to work with, it seems like a no brainer to install a diesel


the boat is a 1979 Catalina 27 tall rig, which has a displacement of 6,850lbs, and a waterline length of 21.75 feet and simple math says that I have a hullspeed of around 6.5kts and that a diesel in the neighborhood of 12-16 horsepower is ideal

with all of that in mind, I am not planning on day sailing or beer can racing, while that may happen, the emphasis of my boat is to take a 1000$ junkyard POS boat and rebuild it to fit my needs to the industry standards....

kind of like how some guys take a rusty old car the found in the junkyard and rebuild it and customize it, I do that with boats, and have done it for years. gets me the most bang for my buck, and as far as my sailboats go, I can usually get in under 1$/mile once its in the water. makes boating affordable to me, and I usually make a killer profit

but this boat is different, I live in Washington state, out in the san juan islands, and have all of that great sailing right at my front door. on a Thursday night, I can even move my boat to the dock at work, so come Friday night once work is over, I can simply untie and take off for the weekend and tie up at the dock at work sunday night and be ready to go for Monday. beyond the San Juans we have BC and Alaska and that's where id like to go. ive done that trip several times on commercial fishing boats, but never in my own boat.

needless to say, the recommended horsepower rating for my boat, seems to be suggested for as the boat sits, with its base weight, and what im wondering is if by bumping the horsepower up to say 20hp of that would be more suited for a boat that will be carrying a 2 people, gear, and supplies for extended trips, and extra fuel, but most importantly, have that extra umph for fighting tides and currents

even locally we have tides that can get going 6,7,8 sometimes 9kts or more

we also aren't seasonal boaters, if I have a boat, it gets used year round, but that still has me wondering about a larger motor being underloaded. id hate to spend my hard earned cash on a motor to under load it and have it die prematurely because it simply wasn't used hard enough, and on the flipside, get an engine that will be over worked pushing a heavier (than your typical C27) boat in strong tides

there is reason why I put a 15hp outboard on the boat origionally, however if I recall those motor are rated for horsepower at some super high rpm number because of the torque curve, so while the boat had a factory option for the M18 universal diesel, which was 14hp, that torque is made at such a lower rpm. I think the recommended outboard motor for that boat was a 9.9 mainly because of the gearbox in the lower unit, but again, I also plan on going long distance.

if the factrory recommendation was 14hp, but plan on pushing a boat with a full load of gear for 2 people up Vancouver island, and potentially through the queen charlottes to the Dixon entrance or even staying in the protected waterways going north, would 6 more horsepower be bad?

sure there are other boats that have better equipment, best suited for the job. my boat aint no Gulf-32, but by Catalina standards, its going to be a tank when im done with it, and that's part of the fun of the project

id love some input to my motor selection

[rbk]

If you're considering taking this boat north for extended trips then find an old diesel and go that route. If you're sticking with the OB then look for a flip up transom mount bracket Kicker Motor Outboard Motor Brackets and a high thrust Suzuki or Yamaha. Pretty sure some of the new 15hp (all 4s these days) have decent stator/rectifiers for electronics and charging. Other brands are also good but availability/interchangeable parts, reliability of the Suz and Yama's are too hard to ignore.

[Chinook92]

this isn't a question of IF I should diesel swap my boat, that has already been decided, the question is will a 20hp diesel be underloaded in a 27 foot boat?

currently have a Suzuki 2 stroke 15hp (might sell it to ya if you are in WA) that was kind of modified to have the controls hook into an Edson binnacle via Teleflex cables with a remote start panel, but did the math, and that diesel will burn about 1/2 gallon an hour, where as that Suzuki will burn 1.5-2 gallons an hour, and I installed a propane system in the boat for a force 10 range and Dickinson heater, and hate hate HATE the idea of gasoline and propane on the same boat.

[a64pilot]

Your a Diesel Mechanic, so you will know that a little oversized won’t harm anything.
In truth you could put my 44 HP Yanmar in there and it would not hurt the motor, but it wouldn’t likely fit and it would likely overload the boat due to its weight.
I’d worry more about what fits and still gives you room to work on the thing and what it weighs.

[GRIT]

I think 20hp would work nicely on that boat. If you're worried about not getting up to operating temperature, you could always get a more aggressive prop. But I doubt very much you'd need it.

I'd take A64 up on his offer, and borrow his engine.

But if you do, you might want a little more aggressive prop, after all, you might as well use all those ponies, if they're there.

I don't think 20hp is too much for that boat at all. A friend has a catalina 28 with 30hp, and he figures it was the perfect size.

I agree with A64, size and weight would be my main considerations. If starting fresh, as you are, I'd put the most hp that would suit the engine room, and weight allowable for such things.

Hp, and money, no-one ever wishes they had less.

Cheers.
Paul.

[Calif.Ted]

The Catalina 270 was equipped with an 18hp. Perkins and later a Yanmar.

[Jim Cate]

Re those 7,8,and 9 knot tidal currents: even with the 20 hp engine, you will be going backward in them... hull speed restrictions don't care too much about extra horsepower!

But fighting headwinds and chop, there the hp will help, and I too think 20 isn't unreasonable for a loaded Cat 27. Careful prop selection will be needed in order to absorb that power usefully, and likely you will end up with a larger diameter prop than standard. The added drag whilst sailing is significant... you might consider a folding or feathering prop while you are at it.

Good luck with the project and the cruising.

Jim

[S/V Alchemy]

Originally Posted by Calif.Ted

The Catalina 270 was equipped with an 18hp. Perkins and later a Yanmar.

I feel like I should advocate for a rebuilt Atomic 4 here, but if you are set on a diesel (which is better for range), you could look at the Beta Marine line, specifically the 14 to 35 HP "drop ins". Why? Because if a Catalina 27 can fit an Atomic 4, and to my knowledge, they all could, then it can fit these diesel replacements for Atomic 4s. http://www.betamarinecanada.com/pdf/A4_guidelines.pdf


I would also add that if you feel you are overpowered, you can enjoy a bigger alternator and more battery capacity. Not a bad problem in cruising mode.

[Ken Z]

yanmar 2ym15 g fresh water cooled

[TrentePieds]

A 20 is fine for a 6K displacement Cat27. As Jim sez, it's headwinds and chop that can make you feel underpowered. TP has a 20 for a laden displacement of about 11K, and we do just fine. In the Salish Sea you have to have constant regard to the tidal flows. There is no way you can buck an 8 knot current in a 5 knot hull speed boat, so engine power is irrelevant then. Deception Pass is a case in point. If you on a fair flow, engine power is also irrelevant since you need very little to make WOG. Why would you try to motor into a 20 knot headwind and a short chop when a mile or two away there is a lovely little cove on a lovely little island with flat water behind it? Where you DO need the engine tends to be in the summer time when it can be dead calm in some places in the Straits and be blowing 12 in some other, nearby places. To get from one blowey patch to the next 20HP is plenty for a Cat27. Years ago, when I taught on Cat27s, a Merc 9.9 OB did us just fine in these waters.

TP

[jen1722terry]

We repowered our Cape Dory 31 two years ago with a Beta Marine 25. We could have put in a 20, figuring the new 20 would have comparable power to the 1984 U-25, but decided that the extra power might be useful.

Glad we did. We sail in Maine, Bay of Funday and Nova Scotia and encounter some strong currents and large seas on the bow. The extra power gets used in those situations. We also wanted the option to put in a larger alternator later on.

The price difference between the 20 and 25 was not great (less than a boat $). Beta was helpful in the install and the block is Kubota, so you can use very inexpensive tractor parts for some repairs.

I converted an old Bristol outboard sloop to diesel many years ago, because I got the deisel for free (fire on a friends boat). It was a nice winter project and, once in, saved a lot of $ on fuel and the hassle of carrying extra gas on long trips.

Good luck. You'll love the diesel.

[SteveSadler]

Inboard engines won't operate at a proper exhaust temp if underloaded. This causes carbon buildup that is a common problem for cruisers that conserve fuel.
Better to run a 10hp at 90% than a 20hp at 50%.
Personally I'd keep the outboard if it's an electric start.
Installing an engine is a big expensive project.

[thomm225]

Originally Posted by SteveSadler

Inboard engines won't operate at a proper exhaust temp if underloaded. This causes carbon buildup that is a common problem for cruisers that conserve fuel.
Better to run a 10hp at 90% than a 20hp at 50%.
Personally I'd keep the outboard if it's an electric start.
Installing an engine is a big expensive project.

Right. Then if you add up all the other things the boat will probably need you may have spent $10,000 before you know it and still have work that needs to be done.

I use a 5 hp outboard on my 6,600 lb Bristol 27. (which is mounted on a bracket which I just replaced)

A friend of mine has a Nissan 8 hp on his Catalina 27 that works great.......it's also on a bracket

And as far as fuel economy goes, the newer, smaller 4 stroke outboards are almost as fuel efficient as a diesel

[Raggedy Man]

When sailing off shore and the weather starts to get rough and you turn into the wind to reef, inboard prop stays in the water.
Universal is a great choice, they are marine adaptions of Kubota tractor engines and you can buy most engine parts at your local lawnmower dealer. Try that with Yanmar.

[thomm225]

Originally Posted by Raggedy Man

When sailing off shore and the weather starts to get rough and you turn into the wind to reef, inboard prop stays in the water.

What?

Why would you turn on the engine to reef?

I head up some but keep sailing. The outboard stays up and out of the water