Seaway coastal cruiser

[Bluejacket]

Hello, new to this site. I own for about a year a Seaway Coastal Cruiser 25. My home water is Lake Erie in Sandusky. I am curious if any other Seaway boat owners are on this site and care to share info. I am new to this type of hull as I always had deep vee boats.
I am curious about propping and motor heights. This boat should cruise at 20 knots and it does but i constantly fight the throttle to keep it there. If I hold full throttle it will get to 27 knots or so but I am definitely maxed out on rpms. At 20 knots I am at 5600rpm. This is on a Suzuki 175hp. Also and I’m sure this is because of lack of knowledge, I can’t trim much because the prop wants to blowout. I’m not sure what my next step should be. All I want is to cruise at a reasonable speed and rpm to not work the motor too hard and be comfortable.

 

[Comodave]

Welcome aboard.

 

[O C Diver]

Welcome to the forum!

Nice looking boat! Could you post some interior pictures, please.

Ted

 

[Bluejacket]

I don’t have any interior pics lol. I will this weekend. Layout is similar to a Rosborough . For a family of 3 it works perfectly.

 

[Dwk]

If @20 kts rpm’s is 5600 what’s rpm @ WOT? Without adding a jack plate can your lower the engine to stop prop from blowing out? Curious…..

 

[Bluejacket]

WOT at 27knots is 6k rpms. It seems to stop at 6k and my speed stays at 27. It’s like driving a truck with 4:10 gears. Revs up and gets loud but no forward momentum. Lol

 

[Bluejacket]

Wanted to mention the motor is mounted on an Armstrong bracket. I need to see which hole it is mounted in.

 

[Bluejacket]

Here are the interior pics

 

[Dwk]

Heater

Interesting looking small footprint heater. What mfg,fuel used?

 

[Bluejacket]

That is a dickenson propane. That runs off 12v. My rooftop unit has heat as well on shoreppwer.

 

[Nick14]

I'm no expert on that particular boat, but have spent a fair amount of time and effort exploring props on several boats in pursuit of optimal performance. FWIW, I looked at that particular model Seaway years back, and am helping a friend buy a similar type boat.

I believe the specs on the Suzuki 175 hp outboard are a maximum operating speed of 6100 rpm, so it sounds like you may be hitting full speed (and presumably engine load) at WOT. If you're hitting 6000 rpm at full throttle, you may be there (+/- 100 rpm could be a clean vs. dirty bottom, load, or weight distribution).

My understanding of the hull of that boat is that it's more of a semi-planing design akin to the Rosborough 246 rather than a full-on planing hull speedboat. 27 knots WOT might be the most you can reasonably expect.

I'm not sure what you mean by 'fighting the throttle' or 'prop blowing out.' If the prop is cavitating or ventilating maybe a cupped prop might help? Perhaps examine the prop and look for signs of cavitation (small pitting along the edges)?

Is the engine sitting too high on the bracket? Is the prop shaft the right length (probably is)? Can it be lowered?

IMHO the design of that boat is fantastic, and superior to anything else in that size range. The Rosborough 246 is very popular, but your boat offers full walk-around deck access, which to be is a HUGE plus for docking, line handling, going through locks, fishing, and generally being able to access all parts of the boat. I don't know of any other boat in that size range offering that (since most people seem to prefer maximizing every single possible square inch of interior cabin space over easy deck access). It's a shame Eastern discontinued that model, but I suppose they thought it too close to and competitive with the Rosborough.

Good luck!

 

[Bluejacket]

Thanks for the reply, being used to a deep vee usually speed is associated with rpms. With this boat after paying more attention this weekend I’m at, 3500 rpms 7knots, 5000 rpms 14knots, 5400 rpms 20knots , 6k rpms 27knots. Those numbers just seem weird to me.

 

[O C Diver]

Thanks for the reply, being used to a deep vee usually speed is associated with rpms. With this boat after paying more attention this weekend I’m at, 3500 rpms 7knots, 5000 rpms 14knots, 5400 rpms 20knots , 6k rpms 27knots. Those numbers just seem weird to me.

If you consider the 7 knot speed as displacement, and pushing a lot of water, the rest seem normal for on plane. Slowing down to 5 to 6 knots would likely have a huge reduction in RPM. 7 knots is probably not a reasonable speed in displacement for a 25' boat. I would imagine once getting up on plane, that 10 to 12 knots would probably be around the slowest comfortable planning speed.

Ted

 

[Carriage Guy]

Rosborough 246 owner with a 200hp Evinrude here.
The web says your engine has a 2.5:1 lower unit gear ratio so your prop pitch will have to take that into account and at first glance does.

Your WOT speeds sound typical for a lightly loaded Rosborough 246 being pushed by a 175 but I agree that the 7 knot speed is probably starting to climb out of the hull speed range and could save you some fuel if you backed off just a little.

Do you have any idea of your current displacement, prop pitch and fuel burn rate at a couple of your higher speeds? Heavy boats will run slower with poorer gas mileage, prop pitch with rpm/speed data points can be used to figure your prop "slip" (inefficient churn rather than forward motion) through the water.
The rule of thumb I've always heard is to simply prop your engine so it achieves it's WOT rpm spec but that spec is a band not a single number.
I've recently come to the conclusion that semi-displacement boats like ours should probably go for the lowest pitch prop that will put their engine at the high end of the WOT spec band in order to minimize prop slip. Like downshifting a car to unload the engine while going up a hill.

True planing boats that are easier to push through the water may do better with a higher pitch running their engines at the lower end of the WOT band. Like driving in overdrive while on the flatlands.

One of the Rosborough forum members recently re-engined with a new Yamaha, lowered his prop pitch from his dealer's initial suggestion and improved both his speed (slightly) as well as fuel consumption.
My Evinrude currently get up to the lower end of it's WOT band and I've calculated my current slip to be in the high 40's% (vs 20% max desired) and am waiting to receive a lower pitched prop. We'll see.
Sounds like your boat may already be set up according to those theories.

 

[kolohe9]

The joys of colored gelcoat

I have an Eastern 27 Islander. (Eastern, Seaway, and Roseborough are all built in the same factory in NH)
I chose to have the gelcoat colored in "Stars & Stripes Blue". It looks great in photos, but the reality is that once it starts to oxidize, it becomes very difficult, (or expensive) to to restore it back to new. The Seaway you have there has an even darker color, and I was just wondering if you have found a way to keep the chalkiness away.
Other members must be having to deal with the same issue as well.
Help!

 

[Miz Trom]

Hello, new to this site. I own for about a year a Seaway Coastal Cruiser 25. My home water is Lake Erie in Sandusky. I am curious if any other Seaway boat owners are on this site and care to share info. I am new to this type of hull as I always had deep vee boats.
I am curious about propping and motor heights. This boat should cruise at 20 knots and it does but i constantly fight the throttle to keep it there. If I hold full throttle it will get to 27 knots or so but I am definitely maxed out on rpms. At 20 knots I am at 5600rpm. This is on a Suzuki 175hp. Also and I’m sure this is because of lack of knowledge, I can’t trim much because the prop wants to blowout. I’m not sure what my next step should be. All I want is to cruise at a reasonable speed and rpm to not work the motor too hard and be comfortable.

Hello Bluejacket:


Hubby and I own a 1987 Seaway 23. We are almost finished restoring her.

Does your hull look like this? Rounded at the stern, with a small keel forward? (Apologies, these were the only photos of the stern I could find)

Ours is a semi-displacement (or semi-planing, depending upon the nomenclature you prefer) hull. Are the newer Seaways like yours the same?

Our Seaway is equipped with a Yamaha 115. I find that her comfortable go-fast speed is 18 mph. Anything over that gets uncomfortable, both for me and the boat. Our Seaway hull was not designed for speed, at least not the high speeds associated with deep-v hulls and large outboards.

I believe that our boat is over-powered. She would do fine with a 90 hp. We recently weighed her. She's only 2100 lbs displacement (not including motor weight).

Also, you might want to contact the manufacturer. They will have done all the testing to find out which horsepower, prop pitch and prop depth aligns best with the hull.

Another good resource for you is the Downeast Boat Forum. There are several Seaway owners there.

Cheers,
Mrs. Trombley

 

[John Haverty 1]

Hello, My name is John. New to the site. I am also the owner of a Seway 25 CC

 

[Bluejacket]

I did send my spare prop to in Indiana and he built that to a 18p prop from the 17p adding more cup as well. My wot numbers are down from 6000 to 5800 add can 3mph to all rpms at cruising speeds . For example I’m at 5000rpm at 18-19 knots . Big improvement and doesn’t blow out any more. Lot my comfortable to drive. Thanks for everyone’s opinions throughout this.

 

[Dyer 29]

Seaway coastal cruiser.

I too had a 2009 seaway coastal cruiser.
We cruised the inside passage with it back in 2011 and 2012. It had the Suzuki 150 on it .it was a great little boat they were built by Harry farmer he build 6 of them 5 in 2008 and 1 in 2009. Mine was the last one built. Harry sold them to Eastern boats and Eastern discontinued the hull in favor of their 248. I tried to get the Bourdeau to let me be a dealer for the 25 but they discontinued it.
I still believe they made a mistake not continuing with it. That was well before the bought the rousbourgh.
My boat had a couple different speeds top speed was 34 mph. But it best cruise was 17 18 knots
6 or 7 knots it siped fuel anything above 24 the semi displacement hull didn't like.
We did a couple thousand miles between Seattle and prince Rupert. Great little boat. I have since replaced it with a Dyer 29
Your boat should just pur at 17 to 20 knots not anywhere close to fuel throttle at that speed.

 

[Bluejacket]

Seaway

Thanks for that info. I still have a lot to learn with a semi displacement hull, coming from a deep vee walleye boat. I’m excited for another year in that boat. Hopefully use it a bit more this year.

 

[Seaway_25]

Greetings from Charlevoix MI -- I also am the owner of a Seaway 25 -- I picked it up near Petoskey MI in late 2014. I think I have hull #2 from 2008 w/a DF175 out back. With the original 3 blade Suzuki prop, I could hit about 28-29 kts, but it would not stay on plane below about 20.. I purchased a 4 blade powertech prop 16 dia x15 pitch from Ken at the propgods and after re-pitching it to 16" I have the ability to stay on plane at around 12-14 kts -- a good speed for rough Lake Michigan conditions. It is a great boat, but a seriously difficult one to dock without a bow thruster and the single screw out back. It cruises very nicely at 20-22kts and is very stable and well behaved at that speed. Above 25kts it gets very squirrely and unstable. You really need a 4 blade prop to get the best low speed performance out of that hull/engine combo.

 

[Seaway_25]

MV Monkey Buckle

In Leland Harbor

 

[Bluejacket]

4 blade

I have a new 4 blade ofs power tech 15p sitting in the closet. It was for a Yamaha but I think I have enough spacers to make it work for a Suzuki. The ofs is only 15 1/4” diameter so I’m not sure what pitch it should be. Always curious if this would help me driving in a following sea. I can’t ever figure out it I should go slow or fast.

 

[Seaway_25]

I looked at some old notes and the original prop that came with the boat on the DF175 was a 16 x 17 three blade. That prop could push it to 29 kts lightly loaded with some bad resonance at 4000 rpm. 29 kts is way too fast for that hull and I could not keep it on plane below 20 kts. The 16 x 16 four blade works way better and allows me to keep it on plane down at 12-15 kt range. You want to run a 16" diameter prop on a DF175. That is how they were designed -- lots of torque and the gearing is optimized for a larger dia prop. Following seas over 3' are quite a challenge in this boat in the great lakes with the steep wave faces. I work the throttle quickly to sort of surf on just before the crest of a wave and being able to slow down to 12 kts helps quite a bit. Crashing the bow down into a 3-4' trough can be quite dangerous and you need to stay on your toes to chop the throttle and quickly steer off at an angle if things get dicey.