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Author Topic:   Recommended power range for 20' Guardian
jxs226 posted 10-29-2003 07:45 AM ET (US)   Profile for jxs226   Send Email to jxs226  

I've searched all posts referencing "Guardian" on this site, searching for the "Official" suggested power range for a 20' Guardian with no success.

I'm currently awaiting the arrival of my two CD's from Tom W. Clark, a purchase spurred by the fact these CD's contain CPD literature from 1988, the year my Guardian was produced.

In the meantine, however, I've stumbled across two possible sources of power for this boat (twin 90 HP's, single 200 HP) and I'd really like to know where each possibility falls with respect to the minimum and maximum suggested power for this hull.

If it makes any difference, this hull has the welded aluminum console, aluminum gunwales with welded rails, tow post, aluminum bulkhead and stainless steel cutwater.

If anyone has access to literature detailing power suggestions for this hull or if anyone has experience powering one of these hulls, I'd really appreciate your thoughts and suggestions.

Thank you,


Plotman posted 10-29-2003 07:45 PM ET (US)     Profile for Plotman  Send Email to Plotman     
From the 1988 whaler commercial catalog:

Max HP 180, Min 85. Single = 25" shaft, twins = 20"

Boat weighs 2390 lbs dry, has 77 gal fuel.

jxs226 posted 10-29-2003 08:03 PM ET (US)     Profile for jxs226  Send Email to jxs226     
Thanks very much Plotman.

I can't understand why the shaft length would differ from a single engine installation to a dual engine installation.

Why would this be?


Perry posted 10-29-2003 08:13 PM ET (US)     Profile for Perry  Send Email to Perry     
Because the single rests in the middle of the "V" bottom and the twins sit outwards where the transom height is less ans a shorter shaft is needed.
jxs226 posted 10-29-2003 08:41 PM ET (US)     Profile for jxs226  Send Email to jxs226     
Right, of course, what the heck was I thinking? Thank you.

180 HP seems a bit low as a maximum HP rating for a hull of this size, no?

Tom W Clark posted 10-29-2003 08:42 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     

Your set of the Catalog CDs went out in yesterday's mail. You should receive them on Friday or Saturday.

I just looked at the 1988 CPD catalog and Plotman reproduces the listed information from there correctly. However, I believe the maximum horsepower rating of 180 is a typo. It should be 200 hp, same as the 20' Outrage of that same year.

All the Guardian's have the same horsepower ratings as their Outrage siblings. 180 hp was the maximum horsepower rating for the original Outrage 20 but the newer 20' hull was introduced in 1986. Surely CPD was using this mold for the Guardian by 1988 and indeed the dimensions in the 1988 CPD catalog for the 20' Guardian match the newer hull, not the older one.

Yes, typos happen in these catalogs. This is not the first.

So to answer your question, 200 hp maximum, 90 hp minimum.

Sal DiMercurio posted 10-29-2003 11:54 PM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
It's 200 hp & the single 200 is faaaaar better then twin 90s.
A good friend has a 90...20' outrage that had twin 70s & was a complete dog in all ways, he went to twin 90s & it's just ok, & thats it, just ok not awsome as it should be.
Get the max hp & you & your boat will be happy.
Just because you have 200 hp dosen't mean you need it all the time, but when you do need it, you have it & you will never look back.
For instace, I have 900 hours on my 200 hp on my "V" 20' Outrage & less then 4 minutes at wide open throttle.
Last year I came upon a boat that this guy couldn't start & I helped him get it running, but I was in Montezuma slough that has locks you must go through to get in or out & they open at 7:am & close at 7:pm until November & I didn't know that they close them in Nov at 5:pm till 7:am & I was about 5 miles from the locks & it was like 12 minutes to 5 & by chance I called the locks in case I had to tow this guy, they sais Sal, we close em up tight in about 12 / 13 minutes.
I ran at 55 mph & got there in time with about 2 minutes to spare.
Had I not had the hp i'v got, I would have had to spead the night there in an open boat till they opened because it's 15 miles to go out the back way & it was a huge minus tide & I would have to run about a total of 30 miles out of my way through the flats of Susiun bay on a minus tide & for sure would run aground.
Get the big hp & like I said, if you need it, it's there, if not, just run the engine nice & easy & it will last you alot longer then if you get a smaller engine.
Fishcop posted 10-30-2003 01:37 AM ET (US)     Profile for Fishcop  Send Email to Fishcop     

200HP Max on the 20' Guardian.
We have a 1986 with a new 175 Yamaha and it is fine for power. My partner has a 1989 with a 1989 200HP Johnson. Lots of power, but sits low in the water because of the weight. Lots of commercial fisherman on the West Coast use smaller twins on the Outrage 20' for economy. It is a lighter boat and they do not care about performance.
Your 20' Guardian is heavier and would benefit from the max HP.
I agree with Sal, go with the big single.

Good luck,


jxs226 posted 10-30-2003 06:40 AM ET (US)     Profile for jxs226  Send Email to jxs226     
Thank you all very much for your advice and clarification.

One of the engines I have a lead on is a 1988 250HP Johnson that's been totally rebuilt by someone I trust. It's too bad 250 is too much HP because the price is right.

Just looking at the 20' hull, it seemed to me twin 115's would be a nice fit, but I guess I was wrong.

I'll try to track down a 200HP.

Thanks again.


JayR posted 10-30-2003 08:24 AM ET (US)     Profile for JayR  Send Email to JayR     
Sal! 55 MPH towing the guy?!?
Got a rocket strapped to the T-top for these emergencies too???

55 towing another boat! Holy Cow!

Sal DiMercurio posted 10-30-2003 10:32 PM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
Jay, I got his engine running & he berths his boat at a harbor at the opposite end of Montezuma slough, & didn't have to go through the locks.
If he had to get through the locks, he wouldn't have made it because he had a 70 hp on an old 18 or 19' Dorset boat.
jimh posted 11-02-2003 10:37 AM ET (US)     Profile for jimh  Send Email to jimh     
I have about three years experience operating a 20-foot classic Boston Whaler hull that is similar to the 1988 GUARDIAN-20 hull. Based on that experience, I would suggest that twin 90-HP engines on a 20-foot GUARDIAN should be a workable arrangement.

The GUARDIAN hull may weigh more than the typical OUTRAGE hull, but I would suspect it does not weight more than the REVENGE, since the latter has a large molded cabin top and foredeck assembly which weighs about 300 pounds.

I have a 1987 REVENGE-20, which has the same hull as a GUARDIAN-20, and it is powered by twin 70-HP engines. This set up has no problem getting the boat on plane. It runs quite nicely, but the top speed is limited to about 34-MPH at Wide Open Throttle. Cruise is most comfortable around 23-MPH. It does require the engines to work; no loafing. I would not call that configuration "a dog in all respects." We recently cruised about 700 miles up and down the coast of British Columbia in the boat and it performed quite well, again the top speed being the only limitation.

The drawback to my arrangement is that you cannot get the boat to plane with a single engine, at least not with the same propeller as you would otherwise be running on an engine as part of a twin engine installation. The ratings list 90-HP as the minimum needed to get the boat on hydroplane. I suspect that a single 90-HP engine, even when equipped with a propeller for use as part of a twin engine installation, would be able to get the boat on plane in typical conditions.

By typical conditions I mean when the boat is not gravid with a full tank of fuel, four 250-pound fishing buddies aboard, 500-pounds of ice in the coolers, rigged with an extensive T-top or other wind-resisting appendages, and crammed with hundreds of pounds of other gear. In that situation, you probably will not be able to push the boat up on plane with a 90-HP engine and its normal propeller.

The break in horsepower rating between 90 and 100-125 seems to coincide with the change from three cylinders to four cylinder engines. This increases the weight of the larger engines. Also, for some reason, in-line four cylinder engines seem to run with more vibration. There are several Mercury models that have limited top speeds, around 5250 RPM, which may be attributed to engine resonances and vibrations from the in-line four cylinder design. There are some V-4 engines in the 100-125 HP range which may be better suited. There is also a problem with some four cylinder engine designs in which the lower idle speed is obtained by shutting down two of the cylinders. This is the case with the Mercury engines in the 115- and 125-HP trim. The transition from two-cylinder to four-cylinder operation has been reported to be a problem.

There are also a number of different engines at the 90-HP rating. Some are small displacement engines which are highly tuned to get additional horsepower. Others are larger displacement engines which have been de-tuned to a 90-HP rating. It would probably be wise to go with the larger displacement engines in your case.

I have given some though to the exact situation you are considering in re-powering a GURADIAN-20. It is a difficult decision to choose between twin engine and single engine.

In favor of the single will be its reduced weight. A single 200-HP engine of traditional 2-stroke design will only weigh about 415-440 pounds. A pair of the lightest 90-HP engines (small displacement Yamaha) will weigh at least 630-pounds, and they will likely have noticeably less performance than the single 200-HP engine.

Also in favor of a single will be the cost. Not only will you save on the price of the engines, but also on the price of the controls, the rigging, the steering, and the propellers.

On the other hand, having twin engines generally provides greater security and reliability, better maneuvering, and better "looks." Twin engines also offer lower draft, which may be a factor in some waters. If you anticipate adding an auxiliary engine to a single-engine installation, say for trolling or "come-home" power, I would suggest that twin engines may be an alternative whose cost is the same.

There have been many intelligent and lengthy discussions in the past regarding the general issue of twin engines versus single engine plus auxiliary. You may want to refer to them.

These are my comments. Again, they are based on my first-hand experience in operating a very similar model of Boston Whaler boat for three years in a wide variety of conditions and waters, including the Atlantic Ocean, the Pacific Ocean, three of the Great Lakes, and numerous large inland lakes.

lhg posted 11-02-2003 05:42 PM ET (US)     Profile for lhg    
Ignoring the 200HP rating on the 1985 and later 20' classic Whaler hull, as I have been known to do, I would say the best option for twin engines is 115's. These should give eqivalent performance of the single 200. Except for Mercury's older in-line 6 115's, at 610lb per pair, all of the current offerings would give a total transom weight in the area of 700lb, which the hull can handle.

On a boat over 10 years old, there is no waranty issue.
One simply has to be sure that the correct insurer is selected.

jxs226 posted 11-03-2003 08:40 PM ET (US)     Profile for jxs226  Send Email to jxs226     
Jim and lhg,

Thank you both for your thoughtful and through replies.

I've now had a many folks whose opinions I value highly give me vastly differing ideal scenarios for powering the 20' Guardian hull.

It seems lhg's view lends some credence to my initial "gut" feeling that twin 115's would be a wonderful match for the hull.

On the other hand, Jim has done an excellent job of outlining some of the major advantages and disadvantages of both single and twin engine arrangements, highlighting the fact that this big hull could perform satisfactorily and very fuel efficiently with twin 70's.

This will be an incredibly difficult decision. I'm thankful and grateful to have access to the opinions and experiences ContinuousWave provides.


mustang7nh posted 11-06-2003 10:01 PM ET (US)     Profile for mustang7nh  Send Email to mustang7nh     
I had a classic 20. 200 hp Johnson 1988 weighed an alleged 465 pounds. Lets be conserative and say its 500 #. There is no way I would put more weight on the back. No, its not because the transom couldn't handle it: it definitely could. I wouldn't do it because of the balance of the boat. I had twin batteries and oil reservior back there which would account for 100 # or so. So I guess you could move them to the console and move up to 550 or 600 pounds. But I would definitely mount the engine high and with a Stilleto prop to lift the boat out of the water.

Can't speak for others, but my OR20 classic would be best with 200 (or same block 225) outboard mounted high on a manual jackplate with high performanc prop. Twin 115s IMO would be way too stern heavy for good performance. Again not a safety issue but a performance issue.

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