Generic SaaS treats your two-year refit like a one-week order, and the maths never reconciles
Bespoke software for a Portsmouth marine-engineering or defence firm typically runs £60,000 to £160,000 over 4 to 8 months. Off-the-shelf SaaS is built for fast, repeatable commercial transactions. Your work runs on multi-year refit cycles, security-marked parts, and subcontract milestones, and no generic tool models that, so you end up running the real business in spreadsheets beside the SaaS you pay for.
You bought the SaaS because the demo looked clean, and now the actual work, a two-year frigate refit or a marine-systems contract with staged milestones, lives in spreadsheets because the tool can't represent it. The SaaS handles the easy 60 percent and the spreadsheets handle the 40 percent that matters, and the two never agree.
Generic SaaS assumes a transaction that opens and closes quickly, a clean supply chain with no security markings, and an org with no clearance constraints. None of that describes a defence-linked marine business on the Solent. You're not missing a feature; you're using a category of tool that was never designed for through-life, classified, milestone-billed work.
The fix: custom software built for Portsmouth, not rented
Bespoke software models the work as it actually runs: a refit as a multi-year program with staged milestones, parts that carry classification and certification, and subcontracts that bill against real contract structures. The 40 percent that lives in spreadsheets comes back into one system, so the numbers reconcile and the audit trail is real. You stop paying for SaaS that only fits the easy part of your business.
The capability list that earns its budget
Portsmouth custom software: the full scope
Everything a custom software build here can cover: bespoke software development, SaaS development, web application development, enterprise software, API development, cloud software and MVP development.
What custom software costs in Portsmouth
| Project scope | Typical cost | Timeline |
|---|---|---|
| Core bespoke system, one major workflow | £60k to £95k | 4 to 5 months |
| Plus security/cert data and milestone billing | £95k to £130k | 5 to 7 months |
| Plus integrations and reporting | £130k to £160k | 7 to 8 months |
How long it takes, phase by phase
Exactly what you get
Software shaped to how a defence-linked marine business actually runs: refits as multi-year programs, parts carrying classification and certification, subcontracts billed against real milestones. The 40 percent that lived in spreadsheets comes into one system, the numbers reconcile, and traceability packs generate for primes and auditors from a single source. It connects to your accounting, CAD/PLM, and field tools so nothing gets re-keyed.
How to choose a developer in Portsmouth
Hire a team that starts by mapping your process, especially the spreadsheet workarounds, before talking features. Ask them to model your refit cycle and milestone billing on a whiteboard. The right partner has shipped for regulated or defence manufacturing and asks about security and clearance early. A team that takes your feature list at face value and quotes a fixed price hasn't understood the job.
- The whole job, including the complex high-value parts, lives in one system instead of split with spreadsheets
- Multi-year refit programs and through-life support are modelled natively, not forced into transaction templates
- Security and certification data is core, supporting audit and traceability for naval primes
- Milestone billing matches your real subcontract structure, ending the monthly spreadsheet rebuild
- The software fits your process, so staff stop maintaining shadow systems alongside it
- Bespoke software is a capital project with a real timeline; you don't get instant value like a SaaS signup
- You own maintenance, security, and evolution forever, which is a standing cost and responsibility
- Getting requirements wrong is expensive to unwind, so discovery has to be done properly
- For the genuinely simple parts of your business, off-the-shelf SaaS may still be cheaper and fine
- !They scope from your feature wishlist, not your process. Ask them to map your refit cycle first
- !They promise a fixed price before discovery. Ask what they're assuming about milestone billing
- !No regulated or defence references. Ask for a project with security-marked data
- !They skip the spreadsheet audit. Ask them to find the 40 percent that lives off-system
- !They under-scope integration. Ask how the new system talks to accounting and CAD
If custom software is on the roadmap, website, inventory management, warehouse management usually follow within the year. Budget them as one conversation.
Rohan advises mid-market and enterprise teams on ERP, CRM and custom software, and has led delivery on dozens of business-software builds.
Writes for Digital Heroes, shipping business software for 2,000+ brands across 55+ countries since 2017.
Frequently asked questions
How do we know if we need bespoke at all?
Count how much of your real, high-value work lives in spreadsheets beside the SaaS you pay for. If the complex 40 percent, the refits, milestones, and security markings, is all off-system, that's the signal that bespoke is warranted.
Can we keep some SaaS and build the rest?
Often yes. The smart pattern is to keep mature SaaS for genuinely standard functions and build bespoke only for the refit, security, and milestone reality nothing off-the-shelf handles, then integrate the two.
What's the biggest risk?
Getting requirements wrong, because bespoke is expensive to unwind. That's why proper discovery, including a hard look at your spreadsheet workarounds, is non-negotiable before a line of code is written.