My first boat - buying tomorrow fingers crossed (advice pls)
- Thread starter TonyBerkshire
- Start date
DavidJ
Well-known member
GRP stands for Glass Reinforced Plastic. It is also called fibreglass, composite plastic or FRP.
TonyBerkshire
Active member
Yes. Understood that.. just the site had them as separate selections.
limecc
Active member
No it's correct.
Using:
21" prop
2:1 gear ratio
4800 rpm
Estimated 10% slip
We get 43mph/37kn
At 25kn cruising speed you'll be around 3500rpm.
QBhoy
Well-known member
Yeah. She won’t do that for sure. The quickest of 99% of boats with a 3.0 in even an 18ft generic bow rider will do well to see much past 40 gps. Early 40’s would be the best possible they see and with a perfectly propped stainless too. With a well suited ally black max prop…I’d expect around late 30’s GPs most often, well trimmed. Especially with a few on board.
HP is definitely 135hp. If she’s the usual gear ratio found on such things…the usual prop would be around 19-21” in pitch. Fact is that if you do want to see her at 40 mph..she might just manage that with more pitch…but you’ll sacrifice being able to plane and cruise well…with the family on board. Add 100kgs of fuel in the tank…worse again. She’ll never be a speed machine…but good enough, efficient, cheap and easy to service, she will be. All the best.
QBhoy
Well-known member
That set up would do well to see 10% slip, I’d think. Be more like 15 with her not being a particularly performance oriented hull and not having the power to get the hull out the water enough to see a 10% or better slip. 40 gps would be great going I’d think.
limecc
Active member
So if it was correctly propped when new and had it's full 135hp, the question is if it will still pull a 21" prop to max rpm? My guess and hope with just Tony in the boat, i.e. lightest possible load and with a clean hull, it will get close. Very interesting to hear how it goes in reality. Start loading her up and like with any small boat a change of pitch is advised.
A 19p and 15% slip gives 32kn/37mph
Maybe running ahead a bit here, but fyi a Turning Point dual geometry 4 blade for the SunRay is only £140 (inc hub kit and vat) from Streamlined Propellers. The 3 blade version is just £95! I just got a Hustler myself, am dying to try it. Good reviews. Could give the old girl her mojo back.
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QBhoy
Well-known member
I’d say the reality might be very similar to what you have predicted here. Given the 19ft heavy hull.
a 4 blade would almost certainly lose efficiency and top end, over a 3 blade. I’d perhaps see how she goes with a 3 blade 19” and take it from there. But real world…late 30’s touching 40 gps would be good going for sure. Like I perhaps said earlier…might be a mph or two above 40 to squeeze…with an inch or so more pitch…no fuel and just the skipper onboard…but what use is that most often ? Best to be more suited to being useable I’d think.
my wee bowrider will at her best run at 68 mph gps…but the prop pitch that will allow that means it’s useless with the family on board or even fuel in the tank or the bow seats fitted. So I sacrifice speed for useable…run less pitch and a more sensible mid 60’s ?…but she’ll plane easier and cruise nicely. Perhaps an exception of a boat…but you get the point.
Bigplumbs
Well-known member
These are the Specs.
Top speed would vary how many on board but it woul be around 32 knots
Engine Horse Power is 135 hp it is a 3 ltr just like the one I had
Material is called GRP Glass reinforced Plastic or more commonly known as fibreglass
the person who said over 200 hp is totally incorrect
Bigplumbs
Well-known member
It is of course up to you but don’t mess with the prop. If it has the original prop it will be correct for the boat. Some people get obsessed with props. Just use it as it is and see how it performs With that 3 ltr and what will almost defo be a Mercruiser Alpha 1 gen 2 outdrive this boat will never be a speed demon no matter what you do.
this set up was put in huge numbers of boats and was the entry level set up. Quite simple and robust for an inboard.
The 4.2 ltr Mercruiser V6 is where it started to be a very fast boat. The engine you have is a straight 4 and is very good but very standard and as I said with one or 2 people should hit 32 knots but no more. If the hull gets heavily fouled and with several people on board it could struggle to get on the plane.
I had that exact engine and out drive for several years in a slightly larger boat and only sold it in 2021 as I replaced it with a 200 hp V6 outboard. That one hits 46 knots with one on board. The boat I sold would only hit about 30 knots as it was a bit larger than the one you just bought
this set up was put in huge numbers of boats and was the entry level set up. Quite simple and robust for an inboard.
The 4.2 ltr Mercruiser V6 is where it started to be a very fast boat. The engine you have is a straight 4 and is very good but very standard and as I said with one or 2 people should hit 32 knots but no more. If the hull gets heavily fouled and with several people on board it could struggle to get on the plane.
I had that exact engine and out drive for several years in a slightly larger boat and only sold it in 2021 as I replaced it with a 200 hp V6 outboard. That one hits 46 knots with one on board. The boat I sold would only hit about 30 knots as it was a bit larger than the one you just bought
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Bigplumbs
Well-known member
Please note also in the advice you are getting some people are using Knots and some MPH when it comes to speed I am sure you are aware that they are different 32 knots = about 37 mph
TonyBerkshire
Active member
Thanks.. that ties in with some of the spec sheet evidence posted on here recently ?
TonyBerkshire
Active member
I must admit I'm somewhat an adrenaline junkie.. bought my latest car with 400hp v8... been working on it to get to 1,000hp (saw someone in the states do it and thought why not ?)
However, safety is always my top priority and yes no plans on making her faster or messing with the prop. Plenty boat to learn the ropes on and want the girls to enjoy it too.
Edit: just seen more previous posts pop up... limecc seems convincing... thinking if this is a basic build sea ray then perhaps it doesn't have the optimal parts?
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TonyBerkshire
Active member
Yes, first thing I checked was 1 knot = 1.151 miles per hour ?
Bigplumbs
Well-known member
It will have the optimal parts If it is how it came out of the factory. It is important that you listen to those that have had, used and operated this type of boat, inboard and outdrive. You can mess with them all you like all you will do is spend quite a lot of money and achieve little extra or most likely nothing. Boats are not like cars. Once you get to about 32 knots it needs one heck of a lot of extra to get say 10 knots extra.
besides you will soon find that the speed you like travelling at most of the time is about 22 knots.
My advice from someone who has several boats of this type and has been boating several years is steer clear of all the copy and pasted theory advice. Don’t go sodding around with props and use the boat as it is for at least a year (Probably only 10 ish trips). Then think about where you want to go with things.
You need to build experience for your self first
You will of course listen to who you want and do your own thing. It is your boat after all
paradave
Well-known member
10ish trips? From that I’d suggest that someone with less ‘experience’ may actually have a lot more real knowledge if they were to use their boat more often.
Fwiw Tony, our current boat was used in excess of 30 times in its first year and we’ve put over 200 hours on her over 2 years. Good luck enjoying it as much as you want.
Fwiw Tony, our current boat was used in excess of 30 times in its first year and we’ve put over 200 hours on her over 2 years. Good luck enjoying it as much as you want.
Bigplumbs
Well-known member
I am sure in time Tony will find out who gave good advice and who did not.
Bigplumbs
Well-known member
My estimate of times used was taking into account it is an open boat I understand he will probably trailer launch and I am sure I read that he said he was a very busy person with work. If any of these are incorrect then perhaps from experience the number might move to around the 15 trips mark. Of course Tony will find this out
DavidJ
Well-known member
Eagerly awaiting the results of your negotiation.
TonyBerkshire
Active member
True.... Good getting a range of thoughts, ideas and experiences for me to make informed risk based decisions.
