Hello from Victoria BC.

The friendliest place on the web for anyone who enjoys boating.
If you have answers, please help by responding to the unanswered posts.

Peter Knowles

Nov 6, 2016
Vessel Name
Vessel Make
1953 38' Monk Tricabin
Hello all, my name is Peter Knowles and I'd like to introduce myself.
I'm a lifelong boater, sailed since a young lad. Now restoring and living aboard a 1953 38' Monk cruiser in Victoria BC.
I have ambitious cruising plans for the PNW and then possibly an overland ride to the Great Lakes and a few loops around America's Great Loop.

It seems passagemaking in wooden boats is a thing of the past, but I'm the sort of fellow to endure the perils.

I hope to be an active participant here in time.

Best Cheers

Welcome aboard eh? Um, your avatar description lists Geordie as an 1853. Might want to change that...
Greetings Peter...from across the strait. Welcome. I have only been here for a short time, but have learned a volume. There are many wise ones here.

So, what powers GEORDIE?

See you out there -

Thank you for the welcome and kind words.

Thanks for the welcome neighbor, had Geordie out at Vector boatyard last spring.

Thanks, Geordie is old, but perhaps not quite that old.

Appreciate the welcome. Geordie sports a Perkins 6.354 which proudly propelled us all through the southern Gulf Islands this summer. But I suspect, given ambitious cruising plans, a BetaMarine 60 is in our future.
Geordie sports a Perkins 6.354 which proudly propelled us all through the southern Gulf Islands this summer. But I suspect, given ambitious cruising plans, a BetaMarine 60 is in our future.

Peter, I would really like to hear more about this. The Perkins 6.354 is rated at 112/120HP and the BetMarine 60 is rated at 56HP, I can't get my head around a HP drop to half of what's in the boat.....:confused:
Hi Mike,

Damn I hate vBulletin forum software, always seems to lose my typing.
Just rewrote this entire post!

You have a valid point and I admit I only mentioned the Beta 60 casually, I’m also considering the 90.
But I do believe the boat is overpowered.
At hull speed of 8 and change the engine is only at about 1/3 throttle and at what I like to think of as a wake based efficient speed of about 7 knots the big Perkins is only ticking over. Several sources estimate hull speed load at about 42hp.
Now having lots of experience at sea I understand there are times when reserve power is required, but I consider that emergency situations. And in those situations, roaring past recommended RPM is justified.

I also believe peak engine efficiency is at peak torque, in the case of the Beta 60, that’s 1700 RPM giving 42 HP, my magic number for hull speed. Less a little for mechanical loss takes me to my favorite wake based speed.

This also puts me squarely in the 70% loading that diesels love.

So on paper the 60 is perfect, the 90 only buys me some more oomph against headwinds.
Plus an extra $5K and a rather tight fit.

Welcome your, and everyone else’s thoughts.

I should say that I am resistant to knee jerk overpowering, I recently hauled a 24’ Airstream all over North America with a 1962 Land Rover,........OK, it has a Chev V6 but still only about 160hp.
Some of the story here,...Travels With Geordie

I should add,

The boat was renamed after my dog Geordie. who I will lose soon.

My previous travels by road are documented in a blog named Travels with Geordie, with apologies to John Steinbeck. In this way, even when he's gone, I'll still be "travelling with Geordie"

The blog stops dead the day I arrived in Victoria, almost two years ago,...
I guess it felt like home,...

Hope that clears up any confusion,.....

Last edited:
Welcome Peter to the "Clan"!
We may of seen you during the summer during our trip.
Hope you are able to provide all of us with your stories and more importantly, a different perspective.

Welcome to you and your lovely boat!
Peter, welcome to TF. You live and boat in one of my favorite places in the whole PNW.

Welcome! It is great to see another wood boat caretaker on the forum. Think I may have seen you around Montague/Saltspring this last summer.

Your re-power plans are very intriguing. Is it a matter of fuel consumption, size, weight, noise or something else? I have been kicking around the idea but cannot seem to justify the cost vs benefit in my case. Those are a lot of boat bucks that I can use somewhere else.

Welcome Peter. A friend of mine has a 1948 Monk here on the Columbia River. Looks just like yours. Great boat.
Thank you all for the kind welcomes.
This is such a friendly place.

Bob, the repower is for a number of reasons, principally reliability.
I love this old Perkins but it's had some abuse, the boat was neglected by the previous owner and seawater rose to destroy the original oil pan by electrolysis.
I don't think anyseawater ever got pumped through the oil passages but I cant be sure.
Every system on the engine has been patched together, it's keel cooled, awkwardly.
I have to start it on ether to avoid a smoke plume and a slick in the water.
Once running, it's sweet and almost smoke free, love the sound!

When I had it out to replace the oil pan, I saw they had cut the floors (wooden boat speak for beams tying the frames together) right down to the frames to fit this beast in, all strength lost.
So although the cost is frightful, I really want to restore those floors and have the peace of mind.

If you're interested there's a thread about the restoration and a little about the engine in a thread on the WoodenBoat Forum.

Not everybody here is addicted to HP. However my knee jerk input is to think in terms of 75 to 85hp and 50 to 60% load. With 60hp you probably won't want to run at hull speed. Most all FD boats operate at one knot below HS (where drag is much less) and many aren't even capable of HS.

IMO you should need about 6 or 7 hp per ton of displacement. That may vary a bit re hull design. Full Displacement boats require 3 to 5hp per ton. My boat is FD and 8 tons .. requires about 4hp per ton. I've got about 5. And don't quite need that. Your boat is SD and if she was an average trawler she'd need 1.5 to almost twice the power of a FD boat. Yours should be closer to 1.5 times as much power as a FD boat.
Consider how much power the old Monks had in the day w their flat head gas engines. That could be a good yardstick.

I'd be looking up Klassen to consider Isuzu and Mitsubishi line of engines. Klassen in Seattle (where I bought my Mitsu) has been absorbed by Hatton in Ballard/Seattle. Klassen may be alive and well just south of Vancouver. They service the north fishing fleet and have since the 60's. They will have an engine for yo much cheaper than a Beta w much better service. If they still exist. Klassen became Yukon Power Systems in Seattle under the Hatton umbrella several years ago. You could call Jim Schiller at 206 784 0148 for further info. Or source Klassen in Canada. Don't know if it would be economically effective to import from Yukon.

Welcome to TF. I'm across the channel in LaConner.

Love the new look.
I never liked forward fly bridges, but I do like my lower, aft cabin bridge deck.
Much more demure.

Good question re. bonding.
I'm completely rewiring and am paying very close attention to this critical issue.
I've removed all the bonding for now, and will probably stay that way, but will be using a high tech voltage balancing system for key structures.
I'm fastened with clinched galvanized nails which are still in very good shape and I want to keep them that way. Because I won't be able to remove them to refasten and I don't want different metals.


Thanks for your thoughts.
Although I'm relatively new to power boats I've given it a lot of thought.
My natural inclination is that semi displacement is a marketing term.
To me if you're not up on a plane, you're sitting in the water.
Now there are certainly better bottom shapes, and the slipperyest is a canoe. pushing the water apart at the bow and allowing it's natural return to pinch the stern along forward. Problem is if you try to exceed hull speed you create a big void because the water hasn't returned against the hull in time. Thus massive wake.
Monk and others at the time, developed better bottoms to allow their boats to be pushed past hull speed without so great a loss, and you are correct, mine is a very sweet shape with a deep forefoot and almost flat at the transom only drawing a few inches.
This being a good improvement the canoe which rolls like a bugger without too much loss of efficiency.
But in the end I never intend to operate at any speed over hull speed, 1/3 throttle gives me hull speed, wide open gives me 2 more knots. And a tidal wave of wake.
I completely agree with you that an ideal speed is a bit below hull speed, it's so easy to judge it by the wake.
And yes, I also agree with your 3 to 5 HP per ton for a displacement hull.
Where I'm confused is where you indicate more power for a semi displacement hull. Is that for the same speed or a greater speed that is potentially achieveable?
The question would be, is my semi displacement hull any less efficient at say a knot below hull speed than a full displacement. I suspect it is, but only marginally. Can it really need 1.5 the power?

If I use 5 HP per ton, 9.5 X 5 = 47.5 HP.

I know the old Chrysler Crown had well over 100 HP, but in that era, throwing fuel away to achieve another knot or two was irrelevant.
I think it was way more than necessary for hull speed or that magical sweet spot slightly slower.

The power curves for my Perkins gives 50 HP at just over 1000 RPM!
But sadly peak torque at about 1800 RPM.
Poor thing is just carboning up.

Now in the end, all things being equal, I'd happily pop in 90 HP, "just to be safe" but my budget and the available space make that difficult.
Those old flatheads were pretty short.

Perhaps your engine recommendations will help me with those issues.
I'll look intro it.

Thanks again, great discussion.

The difference in drag between a FD hull and a SD varies a lot as there are so many variations of SD. Some SD hulls are just about FD and others plane quite nicely at 1.5 to 2 times hull speed. The Monk is a slicer w a narrow easy entry and the whole hull being rather narrow and w soft chines she should or would be about as efficient as a FD but the flat transom sits deep in the water and unlike a canoe the water dosn't flow back to the way it was .... It tumbles out from under the transom/bottom edge. A washing machine wake I call it. FD flows smoothly. SD froths and tumbles. The important part is the aft end of the hull. Not the forefoot.

Re your question "is my SD hull any less efficient at say a knot below HS than a FD?" Yes .... very much so. IMO your SD hull is considerably less efficient a knot below HS than a FD. And your SD hull is more efficient a knot above HS ... and almost certainly at HS. Close to HS there's no speed/drag advantage to FD.

You obviously know more about this than most on TF but you would benefit by looking at the Monk as a SD boat. However most SD hulls are not as efficient as your boat.

Here's a boat similar to yours (but wider) that's diesel powered. She's at LaConner but I don't know how much power. There's another old CC that has been repowered w twin Yanmars. Again I don't know the power or performance. The CC is for sale ($20K) so in that case I could find out about power and performance.

Pics wouldn't come up.
Last edited:

I know what you mean about the transom churn, mine is only a few inches deep, leaving a relatively nice clean exit. I often wonder if at close to hull speed, the returning bow wake is actually lifting the stern to the point where it exits at sea level. I speculate this because I have no "spilling" of water at the sides into a "trough" created by the boat. It's all wonderfully flat.

I'm going to get an optical tach and experiment in calm seas with various speeds. Check them against my 6.354 curves and see if it really is as easy to push as I think.

I do have a propeller problem though, too much pitch, too much froth.
My feeling is a big 4 blade 24" modern wing style should cavitate less.
Pitch is 16" with a 1.91:1 Velvet drive

Too much pitch?
What's your WOT rpm and your rated rpm?

Don't really know, no tach, but the curves I have suggest WOT of 2800
I cruise at under 1000 by ear @ 7 knots.

I know the old rule of thumb that if the engine cannot achieve rated WOT RPM it's over pitched.
I cant confirm until I get a tach but I can wind her up pretty damn fast with no real increase in boat speed.
But in my experience an overpitched prop cavitates, or at least just makes a churning frothy mess.

Wouldn't it be better to work back from an acceptable prop slip?
What is appropriate for a displacement boat?

To get the right amount of "slip" most w trawlers choose a prop w about .75 X the dia. Like 24" dia X 18" pitch. Too much dia and too little pitch like 24X12 means there is too much blade area and too much surface area friction drag. On the other hand too much pitch like 19X21 would have too much water at the blade tips spilling over to the other side loosing pressure differential that would otherwise create thrust. And a 4 blade prop should only be used if a 3 blade w an appropriate pitch/dia ratio lacks blade area. The 4 blade is usually used on a trawler if there isn't enough room for a 3 blade w the right blade area.

Re FD my boat has 40hp, 8 tons, 27.5' WLL, 3000rpm rated power, 6.15 knots cruise at 50% load w 2300rpm. A BW gear w 2.57-1 and an 18X13 prop. The prop was 18X14 but couldn't get close to rated rpm. Took out 1" pitch and am still about 25-50rpm short and have called that good enough. At the next haulout I'll cut the leading edge of the prop back perhaps 1/16" to 1/8" and hope for 25-50 rpm above rated.

I once had a wild/crazy idea of cutting the power in half of an overpowered trawler by removing half of the pistons, valves, ect ect as a poor man's way to cut the power to weight ratio in half. A GB36 twin may run at 50-60% load and 6.5 to 7 knot cruise. Just a guess but the sometimes overheating #6 cyl may forever run cool depending on what cylinders were choosen to be closed off. Never heard of it being done and mention it just for laughs.

These are my opinions and there are some here that have different opinions but I think most (close to all .. or all) engine manufacturers would agree. There is lots posted in the past on engine and prop choices so go surfing.
Welcome aboard, from up-coast a wee bit :thumb:
Thanks for your sage thoughts.
Lots to think about.


Latest posts

Top Bottom