Achilles SG-156 : first trip

[Right Turn Clyde]

We picked up a well cared for 2007 SG-156 this spring from California, and recently got around to breaking it in. Mostly the break in was on a Tohatsu 60hp, and on fitting our whitewater rafting frame/outfit to the boat.

The boat offers the equivalent of about a 14' self-bailing raft, and so we fitted a smaller home brewed frame to it. The outboard is below the weight limit of the motor, but slightly above the hp rating (which makes me glad I don't live in the UK).

Unfortunately, the dealer (Boat Specialists) installed a 9 pitch prop. The result has been a top speed of 21-22mph according to gps. We are planning to switch to a 13 pitch.

The images show its christening (Miller Lite borrowed from a party at the dock), initial testing of frame/cooler setup, and loaded on our recent 5-day exploring of Lake Powell. Powell has ~2,000mi of shoreline, and is a remarkable place to probe on a boat. We did 100mi, and were very pleased with the whole rig...except that prop.

We saw ~5.5-6mpg in mixed speeds, which seems a tad low. I would also like to add a tiller extension for control and to reduce the vibrations coming through. I estimate the fully laden boat to have been 1700lb (it is rated for 2819lb).

The SG is a nice boat, but our motor is mounted a bit too low, so we have yet to experience what it's really like. However, I will say that it leans and carves turns like a motorcycle, which was pretty sweet. Perhaps with the new prop and motor raised 2" it will hit 30mph?

[Right Turn Clyde]

Pictures

[tinker]

That looks a right beast, 60hp on a tiller! 9 inch pitch seems very low, what's the weight of the boat?

Lovely rig BTW, the van and the boat look a perfect combination of fun, add the location, your very lucky.

[Peter_C]

Jealous of the van! I have a Chrysler Town and Country I use for vlamping.

Personally I would ditch the frame as I like to drive from the starboard side tube and sitting on metal looks uncomfortable. I do understand the passenger liking to be inside the tubes on a soft seat. My wife kinda hated our 14ft Zodiac until I bought a frame and seat to put inside for her. We removed the seat for scuba diving.

Maybe you can modify your current frame? They are not super expensive to buy though.
https://www.boatstogo.com/seating-platform.asp

White water kayaking is one of my hobbies

[Right Turn Clyde]

Originally Posted by tinker

That looks a right beast, 60hp on a tiller! 9 inch pitch seems very low, what's the weight of the boat?

Lovely rig BTW, the van and the boat look a perfect combination of fun, add the location, your very lucky.

1700lb in total.

I just ordered an 11 pitch to step up the gearing a tad. We shall see if that let's me run the desired 25-26mph.

[Right Turn Clyde]

Originally Posted by Peter_C

Jealous of the van! I have a Chrysler Town and Country I use for vlamping.

Personally I would ditch the frame as I like to drive from the starboard side tube and sitting on metal looks uncomfortable. I do understand the passenger liking to be inside the tubes on a soft seat. My wife kinda hated our 14ft Zodiac until I bought a frame and seat to put inside for her. We removed the seat for scuba diving.

Maybe you can modify your current frame? They are not super expensive to buy though.
https://www.boatstogo.com/seating-platform.asp

White water kayaking is one of my hobbies

I had a plywood 'topper' made for a big Action Packer box, and used it for a starboard tube seat. Not bad.

These Sprinters are the bomb for posh travel/camping. We had a 1998 AWD Town & Country van that was also great. But stand up height is now a tad better.

[Peter_C]

Originally Posted by Right Turn Clyde

1700lb in total.

Hmmm...I am having trouble believing your boat with all that camping gear weighs that much even with the trailer. My previous 14' Zodiac with a 40hp 2 stroke weighed in around 500lbs going into the water albeit without camping gear. I can see from the photo you pack more than us though.

The SG-156 is 272 pounds. Tohatsu is around 220lbs. That would be a lot of beer in the cooler

We didn't have half the room inside the boat for camping gear though. Talked to my friend about going back to Shasta Lake for some boat in camping in a month or so.

Originally Posted by Right Turn Clyde

I just ordered an 11 pitch to step up the gearing a tad. We shall see if that let's me run the desired 25-26mph.

I would see around 28mph in choppy water with just me onboard. You might be able to play around with motor trim to see how bow rise and speed changes.

Head height in my Town & Country REALLY sucks, as in I can't sit on the bed upright! After a brand new air mattress leaked and my wife grumped, I cut a comfy tri-fold 6" thick mattress down to 48" width, and bought an Amazon steel bed frame and modified it to 48" and to be flat against the un-level floor. It allows me to put my bike or scuba gear under the bed, with bins for camping gear. With a passenger side swivel seat, porta-potti, and a diesel heater the wife has less reasons to dislike camping. Also added a Nomadic 270* awning since I stole one from Ebay for $103, then bought one wall, and have plans to enclose it into a tent for added bug free dry space. I bought the van with blown head gaskets for scrap metal prices to tow the boat, and don't drive it much at all. Someday I might build a nicer Transit out, and have been dreaming of doing so for years. The wife says we can stay in a lot of really nice hotels for what a new van costs though, and she is right.

[tinker]

Originally Posted by Right Turn Clyde

1700lb in total.

I just ordered an 11 pitch to step up the gearing a tad. We shall see if that let's me run the desired 25-26mph.

Might be worth getting a tachometer fitted, there cheap as chips on ebay and very easy to install. It will allow you to see what's going on with the Prop performance/engine revs.

This type of thing

Yooreal Digital Inductive Tachometer with Hour Meter,RPM Gauge Meter for Lawn Mower Scooter Dirt Bike Tractor Generator Air Compressor Marine Motorcycle Snowblower Pressure Washer https://amzn.eu/d/7r8QlOY

Van conversions, did one 2 years ago on a ducato base, USA call it a promaster. I can sleep across it without the pods ( not widely available in the UK) . Took 12 months, about 1000's hours and loads of cash for the improvement bits, batteries , fridges etc. I can see your wife's point on the hotels .....

[Right Turn Clyde]

Originally Posted by tinker

Might be worth getting a tachometer fitted, there cheap as chips on ebay and very easy to install. It will allow you to see what's going on with the Prop performance/engine revs.

This type of thing

Yooreal Digital Inductive Tachometer with Hour Meter,RPM Gauge Meter for Lawn Mower Scooter Dirt Bike Tractor Generator Air Compressor Marine Motorcycle Snowblower Pressure Washer https://amzn.eu/d/7r8QlOY

Van conversions, did one 2 years ago on a ducato base, USA call it a promaster. I can sleep across it without the pods ( not widely available in the UK) . Took 12 months, about 1000's hours and loads of cash for the improvement bits, batteries , fridges etc. I can see your wife's point on the hotels .....

10-4. I put one on, and so have been monitoring rpms (initially just for the break in). Should have the new 11 pitch in a couple weeks, by which time our quagga mussel "dry period" quarantine will be ending, and I can put her back on the water.

[Right Turn Clyde]

[QUOTE=Peter_C;874191]Hmmm...I am having trouble believing your boat with all that camping gear weighs that much even with the trailer. My previous 14' Zodiac with a 40hp 2 stroke weighed in around 500lbs going into the water albeit without camping gear. I can see from the photo you pack more than us though.

The SG-156 is 272 pounds. Tohatsu is around 220lbs. That would be a lot of beer in the cooler

We didn't have half the room inside the boat for camping gear though. Talked to my friend about going back to Shasta Lake for some boat in camping in a month or so.


I did an Excel sheet to add up all the gear, fuel, etc. The tally was 1565 pounds all in. Stuff adds up, but, yes, the 1700 figure was a bit high.

Frankly, I was disappointed to hear the Boat Specialist parts guy keep saying how I WAS "heavily" loaded for that boat/motor combo. It just doesn't make sense to me (as an admitted newb to SIBs and outboards) that I could be 5hp over the rated max, and 1200lb under the boat's rated capacity, and yet he says I was heavily loaded. My feeling is that he was covering for the salesman who spec'd a 9 pitch prop.

Looking today, the motor needs to be raised ~1.5", which should also help matters.

I'd be curious what others think this combo should yield for mpg.

[Steve509926]

Tinker has hit the nail on head, until you know what the rpm is at wot you won't know what prop will be best suited to your setup.
A tinytach is where I'd start, but that's just my opinion.

[Right Turn Clyde]

Originally Posted by Steve509926

Tinker has hit the nail on head, until you know what the rpm is at wot you won't know what prop will be best suited to your setup.
A tinytach is where I'd start, but that's just my opinion.

I guess I wasn't clear. I did install a tach. WOT (6000rpm) was readily hit/held using the 9 pitch. That resulted in 21-22mph max.

[Steve509926]

Looking at the Tohatsu spec for a 60hp, 6000 rpm is where you should be at wot.

[willk]

Originally Posted by Right Turn Clyde

Frankly, I was disappointed to hear the Boat Specialist parts guy keep saying how I WAS "heavily" loaded for that boat/motor combo. It just doesn't make sense to me (as an admitted newb to SIBs and outboards)

Inflatable boats are rated for heavy loads - it was one of their original USPs - very hard to sink a balloon. That said, heavily loaded, they need a lot of power to overcome that weight and tube resistance. You can certainly come up a pitch or so on the prop, but IIWY I would focus on getting up on the plane and having the boat trimmed for efficient cruising, at whatever speed that is. Without meaning to sound rude, I'd review the camp gear as well, pare it right back and once you know the boat better, rebuild the loadout.

[Right Turn Clyde]

Originally Posted by willk

Inflatable boats are rated for heavy loads - it was one of their original USPs - very hard to sink a balloon. That said, heavily loaded, they need a lot of power to overcome that weight and tube resistance. You can certainly come up a pitch or so on the prop, but IIWY I would focus on getting up on the plane and having the boat trimmed for efficient cruising, at whatever speed that is. Without meaning to sound rude, I'd review the camp gear as well, pare it right back and once you know the boat better, rebuild the loadout.

Most of the weight was fuel and water. For a 5-day desert trip, we planned for 120mi route, plus 30mi buffer. We got on plane quite readily, just not to a speed we’d like to have the capability of using if conditions allow. But, yep, definitely focusing on dialing the setup more.

[willk]

Originally Posted by Right Turn Clyde

/// just not to a speed we’d like to have the capability of using if conditions allow. ///

Absolutely, and once your load and prop are finalised, you'll be able to work our your most fuel efficient speed, obviously won't be at WOT but nice to have the extra power on a river! Half a day on the water and a refill will tell you a lot