Outboard Well Performance

[Charlie99]

Hello all,

This is my first post here as I've only just discovered this forum. I'm a college senior that's been slowly bringing a gutted 1960 Rhodes Swiftsure 33 hull back to life as a sort of hobby project, and I'm sure to be in need of plenty of advice as I move along with her.

One question that I've been pondering since I took her over is what to do for auxiliary power. The old Atomic 4 was taken out long ago which leaves me in need of a replacement plan. While not opposed to a diesel or similarly powered electric motor, I am very partial to James Baldwin's outboard well design, both for its cost and simplicity. I will be tackling the necessary repairs to the companionway and cockpit over the next month, and if I can make a decision, it will allow me to decide how to go about dealing with the rotten out afterdeck above the lazarette.

What I'm wondering specifically is, how would one of the 9.8 Tohatsu Sailpros compare in performance to the original 30hp inboard? I have no doubts that she would chug along nicely in calm conditions, but what about in higher winds and stronger currents? With such a shallow draft on the boat I hope to be able to explore more inland waterways than would be accessible to many, and with no experience on any similar outboard powered boat I would like to know how she would behave navigating in narrow channels and around bridges, marinas, etc. I have no intention of attempting to power through a chop around obstructions with any sort motor, but my assumption is that on a flat sea, there would be a reduction in the wind and current speed that you could safely navigate through with the outboard vs an inboard. If I were just fitting her out to cross an ocean or sail between anchorages I think it would be a no-brainer, but with my career path still somewhat up in the air, she may spend many years just day sailing and exploring the West coast of Florida, and I would like her to be well suited for it.

There seem to be several Triton and A30 owners here that have happily made the switch, and I would love to hear how your experience with this design holds up, but keep in mind the Swiftsure is between 2.5 to 4.5 thousand pounds heavier than those boats. Hopefully I am underestimating these little motors though, as a complete diesel or electric installation feels like a staggering expense for a boat that is meant to be sailed.

[atomvoyager]

Welcome to the group. Maybe someone else will post their experiences pushing a heavier boat with an outboard motor. But keep in mind that there a lot of poorly designed non-tilted outboard installations that give this option a bad rep. People with different experiences will have different ideas. You may initially choose the outboard because of cost and simplicity and if done right you'll later appreciate the other benefits as I explained in this article:

https://atomvoyages.com/articles/the-im ... oard-well/

I asked a friend who sails one of my A30 Voyager Editions to comment here on his experience using the boat with both a 6hp and a 9.8 so maybe he'll post something. The other boat I've done that would be a closer approximation to yours is the Able 32 but I've lost contact with here new owner. There are links to a video on that job in the above article. There's also a Pearson Vanguard whose owner copied my design using the 9.8 and has been cruising the ICW from I think the Chesapeake to south Florida. He's not on the forum but I've been to his boat when he passed through here last year and he gets by OK. And then there is Jason featured on my youtube channel with his A30 Voyager Edition with only a 6hp motor that motored through the Panama Canal on many other places and is now in Indonesia on his circumnavigation. He is a skilled sailor though which is how he can do that with such limited hp.

9.8hp may seem a big reduction compered to an Atomic 4 or similar diesel but not as much as you might think. Diesels are rated different a 9.8 outboard is closer to that of a 15hp diesel when you factor in the losses. To have success you do need the extra-long shaft, not just the long shaft and a high thrust prop. And the motor needs to be mounted as low as possible to not have the prop sucking air in choppy water. Your speed won't be reduced much by winds under 25k except for the waves it creates. Current will affect both types of propulsion nearly equally since your top speed for either type motor is not that different. When a higher hp diesel's brute force has the advantage most is when there are strong headwinds with significant waves. You'll either avoid those conditions, use sail, or motor sail through it with the outboard and refed main sheeted tight while pinching 25 degrees or so either side of the wind.

[Charlie99]

Thanks for replying. Your website and Youtube posts have been a big inspiration for me in gaining the confidence to take on a rebuild like this. I have had the intention of using many of your practical modifications, including the tilting outboard well, on a boat of my own long before I had the opportunity to acquire one. The reason for my post, however, is that my available time to work on the boat is limited, and with my schooling soon coming to an end I will be transitioning to working full time, so it would be more feasible to save for a more expensive inboard installation by the time she is ready to splash than I originally thought. That said, my passion is, of course, for sailing, and I plan to spend as little time motoring as possible when I am out on the water. The Pearson Vanguard and Able 32 you mentioned are very similar in displacement and hull profile to the Swiftsure, and so that seems like a reasonable proof of concept for my situation. I will keep an eye on this thread in case anyone else has experiences to share, but I think I will continue with the plan of using the outboard well for the time being.

[Andy5466]

Charlie99

As James mentioned above I acquired one of James's Alberg 30 voyager edition total rebuilds. To say I was lucky and the timing was just right for me to purchase this incredible Yacht is an under statement. Although I have no experience with any of the early model inboards which i know provide questionable maneuverability in reverse and can be ill-tempered in general when it comes to providing reliable auxiliary propulsion, I can coment on my experience with the outboard.

The 9.8 extra long shaft (25")provides more than adequate thrust in forward and reverse. When docking or anchoring you will center the outboard and use the tiller for all course changes. When backing out of a slip or perhaps maneuvering in confined spaces (in reverse) I lock the tiller in place (neurtral position) and use the out board for all course changes in reverse as you have almost total maneuverability side to side just like an normal outboard on an unobstructed transom. The side thrust achieved with the outboard can pivot the entire boat with ease.

As to motoring into tide and wind and waves - I have yet to motor my boat in the open ocean but what motoring I have done in coastal waters I have been incredibly impressed. Once motoring near cumberland Island, GA I was faced with 20 knots on the nose sustained and about 1.5 knot of unfavorable current I had 3.5 miles to motor until I was in the lee of the marsh going up the North River and the boat at approximately 3/4 throttle achieved 3.5 knots with no issue motoring into the conditions described with 1 - 2 foot chop. In flat water as described the motor will propel the boat at hull speed easily.

Recently while my 9.8 was in the shop James let me borrow his 6 hp extra long shaft. This motor compared to mine was light and easily removed and installed with one person. It provides adequate thrust in forward and marginal thrust in reverse compared to the 9.8. Not to say it is not manageable it just takes a little more planning when approaching anything you do not want to hit. Motor sailing with the 6 against the wind with no current and moderate chop you will need almost all the power the engine has to offer but if you can fall of one side or the other of the wind to get some drive from the main it really helps. I was totally impressed with the smaller engine mainly because of the weight and size. being a single cylinder it was noticeably louder and produced more vibration than the 9.8 Both motors are extremely fuel efficient. overall I am like you I bought this boat to sail and any chance I get the motor is off and the sails are up doing what they do best. Feel free to reach out to me if you have anymore questions.

Cheers
Andy

[lsheaf]

If I could install an inboard well on my boat, I would. Unfortunately due to the design of my transom hung rudder I’m limited to either an inboard diesel or offsetting an outboard bracket on the transom. My diesel has run really well since I bought the boat (besides the propeller being slightly undersized) but I do not like the complimentary oil leaks. Removing the diesel would give me a lot of extra storage which could accessed from inside the cabin underneath the companionway steps, no more oil leaks, and less expensive repairs.


In terms of propulsion power, The only experience I have propulsing my boat (an Allied Seawind 30) with an outboard is when hip towing. That was carried out with a 12ft inflatable / 15hp Yamaha two stroke. I have hip towed the boat through 3 knots of current and 15-20 knots of wind at around 3-4 knots (also with a dirty bottom).

I suppose if you were cruising long distances, an “inboard well engine” could double as your tender engine as well. But it may be awkward to remove and install the engine frequently.

[Charlie99]

Andy,

thanks for taking the time to reply. I appreciate the tips on maneuvering with the outboard, hopefully they will save me any potential embarrassment when I get around to splashing her. The ability for side thrust of the engine seems like a big benefit in my mind, and in my experience on smaller vessels has helped prevent more than one brush with the dock.

Like you, I intend to only use the motor for coastal navigating, and your story about going past Cumberland Island is exactly the sort of reassurance I was looking for in terms of the capability of this arrangement. I would be hard pressed to attempt navigating past lee obstructions in conditions much worse than described, even with a higher powered inboard. Seems to me that the 9.8 will be fully suitable for any motoring I would be comfortable with.

I do think that a 6 horse would be perfectly viable for longer passages where you have the luxury of waiting for fair weather and spend less time in port, however, at least for the beginning I will be sticking with the 9.8/9 design to have that extra bit of thrust as I learn the behavior of the boat. That said, once she is in the water and sailable I have plans to upgrade her systems over time for longer cruises, including intentions for a large lithium battery bank where the original inboard and fuel tank sat. I expect electric outboards will become more accessible and efficient in the years to come and are something I'd be quite interested in, as current models offer similar thrust to the 9.8s in much lighter packages, and can sit securely in what would then be an existing well. Not to mention the complete elimination of noise.



Isheaf,

Thanks for the reply. Having worked on older inboards I understand your frustration. There is a lot to be said for their reliability, but that goes in tandem with a lot of maintenance, and in my boat specifically the access would be horribly limited. I have considered using the primary engine for the tender as well. I suppose it would come down to whether or not the hassle is worth having more than a few horsepower on the back of the dinghy. My boom does extend about to the end of the cockpit, so it may be viable to rig the motor to the mainsheet for raising and lowering, but that is something I'll have to experiment with in the future.

[Grounder]

This is an old post but interesting discussion.

What about just putting a 15hp outboard in? If you can work out the rig to get it in and out safely, doesn't that remove all the worries?

Assuming of course there is space. But a 15hp isn't much larger than a 10hp.

[atomvoyager]

Most boats that have the space for bigger than a 6hp Tohatsu Sailpro only have barely enough space to fit a 9.8hp which is already heavy at 112lbs for the extra-long (25") shaft. There is also no space for power tilt and manual tilt is difficult on bigger motors. In the Tohatsu range the 9.9 and 15hp are the same physical size. Not sure about Yamaha and others. There could be some boats that can tolerate the space requirements and weight of a 15 but you need to measure the motors side by side or look at dimensions on the drawings. By the way, tiller handle length on some motors can be a problem to fit within an enclosed well box.

[MikeDee]

Slightly old thread but I'll chime in anyway.
My last boat was a Swiftsure 33, I now own a Bristol 27 with a tilt up outboard motor well housing a Tohatsu 9.8.
You can buy a Suzuki 9.9 with an extra long shaft then buy the 20 hp engine module that turns that 9.9 into a 20hp motor . The Suzuki 9.9 is larger and 30 pounds heavier than the Tohatsu 9.8 but I believe the Swiftsure has the room if you build a well . I believe you can also upgrade a modern Tohatsu 9.9 to a 20 hp by changing out the computer module as well.